CRITIQUE OF RECENT WORK ON THE MORPHOLOGY 
OF THE VERTEBRATE SKULL, ESPECIALLY IN 
RELATION TO THE ORIGIN OF MAMMALS 
WILLIAM K. GREGORY 
From the American Museum of Natural History, New York 
TWENTY-FIVE FIGURES 
CONTENTS 
721 SRST Tinie S28, SPN OES Be er as at ee 1 
Seeeeeater i aC rirnal HOIRCTUINAN os. og oc ca tera wie oimiatdn w cle uh fon aw ese ose es Flee 3 
Orbitosphenoid, salar et and oe ey ck FT ie SEES DBL ae eae e SEM ren Ps 4 
Reptilian lower jaw.. pene) Bee ASEO ex ot cred Sea ed whet ee 
PM aCL RESIN UNG WET. JU Widen ecco acct fe ea TAY coe AR, eRe les ele eee oo sek ees 18 
PreAMGALIT AUCIDONY*OSHLELES. < os 5 s5 sabes dnp fee eine e sb plore gn el See a ght 23 
SPpraR RPMm CRIM TINEVINITTV ALE 05 SONS a eo site's citeie Sia duc hats eaten MO saa gpe RSIS ialat sa ald Vere Ae Bo 
RAPP EN pt a ete ae mete oc. Se cies Paoli ae ecte pe Rides ikteyeinnd sts, > S/n aa 41 
INTRODUCTION 
To observers who have followed the trend of zoological research 
during recent years it is apparent that zoologists have in great 
numbers turned away from vertebrate comparative anatomy as 
a thankless task and have come to regard its labyrinths as leading 
nowhere. The rise of statistical and experimental research has 
accompanied a reaction against such speculative conclusions as 
those of Gegenbaur and Dohrn and it has been said that neither 
comparative anatomy nor paleontology have told us by what 
steps organs have been evolved but only how they may have 
been evolved. It has even been hinted that our theories of 
phylogeny and morphogeny are too much the product of the 
unchecked imagination, which seizes gladly upon favorable 
evidence but fails to seek the unfavorable. 
1 
JOURNAL OF MORPHOLOGY, VOL. 24, NO. 1 
MARCH, 1913 
