The Securities and Exchange Commission has not necessarily reviewed the information in this filing and has not determined if it is accurate and complete.
The reader should not assume that the information is accurate and complete.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
FORM 13F

FORM 13F INFORMATION TABLE
OMB APPROVAL
OMB Number: 3235-0006
Estimated average burden
hours per response: 23.8
COLUMN 1 COLUMN 2 COLUMN 3 COLUMN 4 COLUMN 5 COLUMN 6 COLUMN 7 COLUMN 8
VALUE SHRS OR SH/ PUT/ INVESTMENT OTHER VOTING AUTHORITY
NAME OF ISSUER TITLE OF CLASS CUSIP (x$1000) PRN AMT PRN CALL DISCRETION MANAGER SOLE SHARED NONE
3-D SYS CORP DEL COM NEW COM 88554D205 1,194 66,494 SH   SOLE   66,494 0 0
3M COMPANY COM 88579y101 712 4,039 SH   SOLE   4,039 0 0
AAC HOLDINGS INC COM 000307108 19,896 1,144,082 SH   SOLE   1,144,082 0 0
ABBOTT LABORATORIES COM 002824100 491 11,622 SH   SOLE   11,622 0 0
ABBVIE INC SHS COM 00287y109 514 8,155 SH   SOLE   8,155 0 0
ALPHABET INC CLASS C COM 02079K107 81,166 104,422 SH   SOLE   104,422 0 0
ALPHABET INC. CLASS A COM 02079k305 678 843 SH   SOLE   843 0 0
AMAZON.COM INC COM 023135106 2,182 2,606 SH   SOLE   2,606 0 0
AMERICAN TOWER REIT INC COM 03027X100 87,644 773,351 SH   SOLE   773,351 0 0
AMGEN INC COM PV $0.0001 COM 031162100 253 1,515 SH   SOLE   1,515 0 0
ANSYS INC COM 03662Q105 130,388 1,407,925 SH   SOLE   1,407,925 0 0
APPLE INC COM 037833100 680 6,017 SH   SOLE   6,017 0 0
APPLIED MINERALS INC COM 03823m100 12 80,000 SH   SOLE   80,000 0 0
ATMOS ENERGY CORP COM 049560105 223 3,000 SH   SOLE   3,000 0 0
ATRION CORPORATION COM 049904105 4,384 10,277 SH   SOLE   10,277 0 0
AUTOMATIC DATA PROC COM 053015103 1,950 22,106 SH   SOLE   22,106 0 0
BECTON DICKINSON&CO COM 075887109 313 1,741 SH   SOLE   1,741 0 0
BERKLEY W R CORP COM 084423102 2,753 47,658 SH   SOLE   47,658 0 0
BERKSHIRE HATHAWAY INC DELAWA COM 084670108 1,297 6 SH   SOLE   6 0 0
BERKSHIRE HATHAWAYINC DEL CL COM 084670702 3,163 21,897 SH   SOLE   21,897 0 0
BIO-TECHNE CORP COM 09073M104 27,574 251,814 SH   SOLE   251,814 0 0
BIOGEN INC COM 09062x103 1,796 5,737 SH   SOLE   5,737 0 0
BLACKBAUD INC COM 09227Q100 67,301 1,014,480 SH   SOLE   1,014,480 0 0
CALAVO GROWERS INC COM 128246105 215 3,289 SH   SOLE   3,289 0 0
CAMPBELL SOUP CO COM COM 134429109 219 4,000 SH   SOLE   4,000 0 0
CANADIAN NATL RY CO COM COM 136375102 1,308 20,000 SH   SOLE   20,000 0 0
CAPITAL ONE FINL CORP COM COM 14040H105 1,839 25,608 SH   SOLE   25,608 0 0
CARMAX INC COM 143130102 97,481 1,827,205 SH   SOLE   1,827,205 0 0
CELGENE CORP COM 151020104 95,641 914,958 SH   SOLE   914,958 0 0
CHEVRON CORP COM 166764100 845 8,212 SH   SOLE   8,212 0 0
CHIPOTLE MEXICAN GRILL CL A COM 169656105 21,115 49,858 SH   SOLE   49,858 0 0
CISCO SYSTEMS INC COM COM 17275r102 2,210 69,671 SH   SOLE   69,671 0 0
COCA COLA COM COM 191216100 1,076 25,414 SH   SOLE   25,414 0 0
COLGATE-PALMOLIVE CO COM 194162103 736 9,925 SH   SOLE   9,925 0 0
COMCAST CORP NEW CL A COM 20030n101 4,095 61,720 SH   SOLE   61,720 0 0
COMPUTER MODELLING LTD COM 205249105 101 13,528 SH   SOLE   13,528 0 0
CORE LAB N.V. COM COM n22717107 2,020 17,985 SH   SOLE   17,985 0 0
COSTAR GROUP INC COM 22160N109 91,907 424,453 SH   SOLE   424,453 0 0
CROWN CASTLE REIT INC SHS COM 22822v101 6,265 66,503 SH   SOLE   66,503 0 0
DENTSPLY SIRONA INC COM 24906p109 256 4,300 SH   SOLE   4,300 0 0
DISCOVER FINANCIAL SERVICES (U COM 254709108 59,420 1,050,746 SH   SOLE   1,050,746 0 0
DISNEY (WALT) CO COM STK COM 254687106 812 8,747 SH   SOLE   8,747 0 0
DOUGLAS DYNAMICS INC COM 25960R105 1,568 49,099 SH   SOLE   49,099 0 0
DU PONT EI DE NEMOUR COM 263534109 329 4,915 SH   SOLE   4,915 0 0
DUKE REALTY CORP REIT COM 264411505 362 13,250 SH   SOLE   13,250 0 0
DULUTH HOLDINGS INC COM 26443V101 1,591 60,001 SH   SOLE   60,001 0 0
EAST WEST BANCORP INC COM 27579r104 312 8,500 SH   SOLE   8,500 0 0
ECOLAB INC COM 278865100 128,655 1,056,974 SH   SOLE   1,056,974 0 0
ELI LILLY & CO COM 532457108 584 7,278 SH   SOLE   7,278 0 0
ELLIE MAE INC COM 28849P100 5,394 51,223 SH   SOLE   51,223 0 0
EMERSON ELECTRIC CO COM 291011104 549 10,065 SH   SOLE   10,065 0 0
ENTERPRISE PRDTS PRTN LPL P COM 293792107 533 19,275 SH   SOLE   19,275 0 0
ENVESTNET INC COM 29404K106 54,577 1,497,322 SH   SOLE   1,497,322 0 0
EQT CORP COM 26884l109 666 9,170 SH   SOLE   9,170 0 0
EQUITY RESIDENTIAL REIT COM 29476l107 362 5,626 SH   SOLE   5,626 0 0
EXPONENT INC COM 30214U102 40,247 788,237 SH   SOLE   788,237 0 0
EXPRESS SCRIPTS HLDG COM 30219g108 1,124 15,941 SH   SOLE   15,941 0 0
EXXON MOBIL CORP COM COM 30231g102 1,829 20,961 SH   SOLE   20,961 0 0
FASTENAL CO COM 311900104 79,953 1,913,657 SH   SOLE   1,913,657 0 0
FINANCIAL ENGINES INC COM 317485100 6,751 227,241 SH   SOLE   227,241 0 0
FISERV INC COM 337738108 6,859 68,953 SH   SOLE   68,953 0 0
FORTINET INC COM COM 34959E109 527 14,263 SH   SOLE   14,263 0 0
GENERAL ELECTRIC COM 369604103 3,445 116,300 SH   SOLE   116,300 0 0
GENUINE PARTS CO COM 372460105 496 4,934 SH   SOLE   4,934 0 0
GOOD TIMES RESTAURANTS INC COM 382140879 97 28,755 SH   SOLE   28,755 0 0
GUIDEWIRE SOFTWARE INC COM 40171V100 544 9,075 SH   SOLE   9,075 0 0
HCP INC COM 40414l109 2,332 61,453 SH   SOLE   61,453 0 0
HEALTHCARE SERVICES GROUP INC COM 421906108 78,253 1,977,093 SH   SOLE   1,977,093 0 0
HEICO CORP NEW CL A COM 422806208 262 4,328 SH   SOLE   4,328 0 0
HOME DEPOT INC COM 437076102 417 3,242 SH   SOLE   3,242 0 0
IBM CORP COM 459200101 1,490 9,381 SH   SOLE   9,381 0 0
IDEXX LABORATORIES INC COM 45168D104 13,884 123,164 SH   SOLE   123,164 0 0
ILLINOIS TOOL WORKS COM 452308109 246 2,050 SH   SOLE   2,050 0 0
ILLUMINA INC COM 452327109 70,643 388,876 SH   SOLE   388,876 0 0
IMAX CORP COM 45245E109 90,264 3,115,760 SH   SOLE   3,115,760 0 0
INTEL CORP COM 458140100 13,598 360,221 SH   SOLE   360,221 0 0
INTUITIVE SURGICAL INC COM 46120E602 109,341 150,851 SH   SOLE   150,851 0 0
INVENTURE FOODS INC COM 461212102 201 21,351 SH   SOLE   21,351 0 0
JOHNSON AND JOHNSON COM COM 478160104 10,759 91,079 SH   SOLE   91,079 0 0
JPMORGAN CHASE & CO COM 46625h100 344 5,162 SH   SOLE   5,162 0 0
KIMBERLY CLARK COM 494368103 299 2,373 SH   SOLE   2,373 0 0
LABORATORY CORP AMER HLDGS COM COM 50540R409 2,504 18,213 SH   SOLE   18,213 0 0
LINCOLN NTL CORP IND NPV COM 534187109 246 5,239 SH   SOLE   5,239 0 0
LITHIA MOTORS INC CL A COM 536797103 286 2,993 SH   SOLE   2,993 0 0
LKQ CORP COM 501889208 178,039 5,020,847 SH   SOLE   5,020,847 0 0
LYNAS CORP LTD AUD PA COM q5683j103 3 75,000 SH   SOLE   75,000 0 0
M & T BANK CORP COM 55261f104 490 4,224 SH   SOLE   4,224 0 0
MAGELLAN MIDSTREAM PRTNRS LP C COM 559080106 255 3,600 SH   SOLE   3,600 0 0
MARKEL CORP HLDG CO COM 570535104 93,180 100,326 SH   SOLE   100,326 0 0
MASTERCARD INC-CLASS A COM 57636Q104 54,446 534,989 SH   SOLE   534,989 0 0
MCCORMICK & CO INC COM NON VTG COM 579780206 1,172 11,733 SH   SOLE   11,733 0 0
MERCK AND CO INC SHS COM 58933y105 1,496 23,964 SH   SOLE   23,964 0 0
MESA LABS INC COM 59064R109 420 3,674 SH   SOLE   3,674 0 0
MICROSOFT CORP COM 594918104 3,420 59,379 SH   SOLE   59,379 0 0
MIDDLEBY CORP COM 596278101 1,636 13,237 SH   SOLE   13,237 0 0
MONRO MUFFLER BRAKE INC COM 610236101 946 15,464 SH   SOLE   15,464 0 0
MOODYS CORP COM 615369105 120,853 1,116,119 SH   SOLE   1,116,119 0 0
NASPERS LTD-N SHS SPON ADR COM 631512100 413 24,800 SH   SOLE   24,800 0 0
NATIONAL AMERICAN UNIVER COM 63245q105 31 15,000 SH   SOLE   15,000 0 0
NEOGEN CORP COM COM 640491106 548 9,800 SH   SOLE   9,800 0 0
O REILLY AUTOMOTIVE INC COM 67103H107 16,684 59,564 SH   SOLE   59,564 0 0
ONEBEACON INSURANCE GROUP LTD COM G67742109 596 41,733 SH   SOLE   41,733 0 0
OXYSURE SYSTEMS INC COM COM 69208T101 0 10,000 SH   SOLE   10,000 0 0
PAYCHEX INC COM 704326107 3,331 57,560 SH   SOLE   57,560 0 0
PEPSICO INC COM 713448108 571 5,247 SH   SOLE   5,247 0 0
PFIZER INC COM 717081103 1,091 32,202 SH   SOLE   32,202 0 0
PHILIP MORRIS INTL COM 718172109 331 3,403 SH   SOLE   3,403 0 0
PINNACLE WEST CAP CORP COM 723484101 228 3,000 SH   SOLE   3,000 0 0
PNC FINCL SERVICES GROUP COM 693475105 2,227 24,724 SH   SOLE   24,724 0 0
POOL CORPORATION COM 73278l105 301 3,188 SH   SOLE   3,188 0 0
POTASH CORP SASKATCHEWAN COM 73755l107 1,960 120,097 SH   SOLE   120,097 0 0
PRA GROUP INC COM 69354N106 51,410 1,488,421 SH   SOLE   1,488,421 0 0
PRICE T ROWE GROUP INC COM 74144T108 10,448 157,114 SH   SOLE   157,114 0 0
PROCTER & GAMBLE CO COM 742718109 19,175 213,650 SH   SOLE   213,650 0 0
PROS HOLDINGS INC COM 74346Y103 35,894 1,587,506 SH   SOLE   1,587,506 0 0
QUALCOMM INC COM 747525103 45,140 658,979 SH   SOLE   658,979 0 0
RED HAT INC COM 756577102 152,650 1,888,529 SH   SOLE   1,888,529 0 0
ROPER TECHNOLOGIES INC COM 776696106 157,786 864,724 SH   SOLE   864,724 0 0
RPM INTERNATIONAL INC COM 749685103 220 4,100 SH   SOLE   4,100 0 0
RUSH ENTERPRISES INC CL A COM 781846209 367 14,980 SH   SOLE   14,980 0 0
S & P GLOBAL INC COM 78409V104 82,040 648,227 SH   SOLE   648,227 0 0
SBA COMMUNICATIONS CORP CL A COM 78388J106 16,832 150,071 SH   SOLE   150,071 0 0
SCHLUMBERGER LTD COM 806857108 12,353 157,082 SH   SOLE   157,082 0 0
SEI INVESTMENTS CO COM 784117103 118,213 2,591,832 SH   SOLE   2,591,832 0 0
SIGNET JEWELERS LTD COM G81276100 63,244 848,574 SH   SOLE   848,574 0 0
SMITH & NEPHEW P L C ADS COM 83175M205 361 11,000 SH   SOLE   11,000 0 0
SOTHERLY HOTELS INC COM COM 83600C103 61 11,625 SH   SOLE   11,625 0 0
STERICYCLE INC COM 858912108 60,518 755,153 SH   SOLE   755,153 0 0
TELADOC INC COM 87918A105 1,603 87,523 SH   SOLE   87,523 0 0
TESLA MOTORS INC COM 88160R101 203 993 SH   SOLE   993 0 0
TRANSDIGM GROUP INC COM 893641100 81,977 283,538 SH   SOLE   283,538 0 0
TRIMBLE INC COM 896239100 87,119 3,050,395 SH   SOLE   3,050,395 0 0
TYLER TECHNOLOGIES INC COM 902252105 94,480 551,772 SH   SOLE   551,772 0 0
U S BANCORP COM 902973304 1,359 31,686 SH   SOLE   31,686 0 0
ULTIMATE SOFTWARE GROUP INC COM 90385D107 359 1,755 SH   SOLE   1,755 0 0
UNDER ARMOUR INC COM 904311107 232 6,000 SH   SOLE   6,000 0 0
UNDER ARMOUR INC SHS WHEN I COM 904311206 324 9,573 SH   SOLE   9,573 0 0
UNITED PARCEL SERVICE INC CL B COM 911312106 256 2,342 SH   SOLE   2,342 0 0
UNITED TECHS CORP COM COM 913017109 428 4,210 SH   SOLE   4,210 0 0
VENTAS INC REIT COM 92276f100 2,136 30,239 SH   SOLE   30,239 0 0
VERISK ANALYTICS INC COM 92345Y106 104,293 1,283,137 SH   SOLE   1,283,137 0 0
VERIZON COMMUNICATNS COM COM 92343v104 360 6,931 SH   SOLE   6,931 0 0
VISA INC CL A COM 92826C839 120,433 1,456,262 SH   SOLE   1,456,262 0 0
W.P. CAREY INC. REIT COM 92936u109 369 5,715 SH   SOLE   5,715 0 0
WABTEC COM 929740108 62,060 760,074 SH   SOLE   760,074 0 0
WAGEWORKS INC COM 930427109 106,041 1,740,949 SH   SOLE   1,740,949 0 0
WASTE CONNECTIONS INC COM 94106B101 70,116 938,636 SH   SOLE   938,636 0 0
WATSCO INC COM COM 942622200 592 4,200 SH   SOLE   4,200 0 0
WAYFAIR COM 94419l101 483 12,270 SH   SOLE   12,270 0 0
WELLS FARGO & CO COM 949746101 339 7,659 SH   SOLE   7,659 0 0
WELLTOWER INC COM 95040q104 377 5,046 SH   SOLE   5,046 0 0
WHOLE FOODS MKT INC COM COM 966837106 448 15,800 SH   SOLE   15,800 0 0
WSFS FINANCIAL CORP COM 929328102 990 27,130 SH   SOLE   27,130 0 0
ZOE'S KITCHEN INC COM 98979J109 270 12,147 SH   SOLE   12,147 0 0
BLACKROCK ENHANCED EQT DIV TR ETFS 09251A104 79 10,000 SH   SOLE   10,000 0 0
ISHARES MSCI EAFE ETF ETFS 464287465 222 3,749 SH   SOLE   3,749 0 0
SPDR GOLD TRUST ETFS 78463v107 201 1,600 SH   SOLE   1,600 0 0
VANGUARD DIVIDEND APPREC ETFS 921908844 1,041 12,405 SH   SOLE   12,405 0 0
VANGUARD FTSE ALL WORLD EX US ETFS 922042775 2,706 59,562 SH   SOLE   59,562 0 0
VANGUARD FTSE EMERGING MARK ET ETFS 922042858 475 12,625 SH   SOLE   12,625 0 0
VANGUARD HIGH DVD YIELD ETF ETFS 921946406 642 8,901 SH   SOLE   8,901 0 0
VANGUARD INDEX FDS FORMERLY VA ETFS 922908363 3,347 16,845 SH   SOLE   16,845 0 0
VANGUARD REIT ETF ETFS 922908553 782 9,015 SH   SOLE   9,015 0 0
VANGUARD SHORT-TERM GOV BD ETFS 92206c102 442 7,225 SH   SOLE   7,225 0 0
VANGUARD TOTAL STK MKT ETF ETFS 922908769 291 2,615 SH   SOLE   2,615 0 0