TOOTH-GENESIS IK THE CANID^. 467 



tunity of doing througli the kindness of Mr. Oldfield Thomas, 

 to whom my best thanks are due for having allowed me to have 

 free access to the specimens in the British Museum. In carry- 

 ing on this part of my investigation I have taken Huxley's 

 monograph, " On the Cranial and Dental Characters of the 

 Canidse" (7), as my guide. 



In this paper Huxley divided the Canidge primarily into two 

 series, the Thooid and Alopecoid, and arranged several of the 

 members in each series in a fairly definite order of specialization, 

 distinguishing the Macrodont from the Micro dont forms. 



It will not be necessary to tnke each member of the series 

 individually. Commencing with the Thooid series, it will be 

 sufficient to examine G. Azarae (SL7 a), G- canerivorus (46. 1.2S. 

 57), C. magellanicus (184 &), G. anthus (8L6a)*. 



pr 



The biting-surface of the First Eigbt Upper Molar Tooth of— A. Canis Azarm ; 

 B. C. canerivorus ; C. C. inageUanicus ; D. C. anthus. (Thooid Series.) 



Fig. 7 delineates the crown of the first rigJit upper molar in 

 eacli of these forms. G. Azarce (A) and C canerivorus (B) belong 

 to the Microdont series, and have the fewest cusps, the former 

 baving six and the latter eiglif ; whereas G. anthus (D) (which 

 with C. aureus belongs to the Macrodont series) has ten cusps. 

 The measurements of G. onapeUanicus (C) appear to vary, but 

 working out the measurements given by Huxley {pp. cit. p. 2u7), it 



* These numbers refer to the particular British Museum specimens from 

 which the drawings were taken. 



