248 PROF. HUXLEY ON THE CRANIAL AND [Apr. 6, 



groups, in one of which the peculiarities of Cants vulpes, while in 

 the other those of C. azarce are always to be met with. 



Similar to C. vulpes are C. fulvus, C. argentatus, O. cinereo- 

 argentatus, C. lit f oralis, C. nilotictis, C. caama, C. zerda, C. lago- 

 pus ; and, on the other hand, C. lupus, all varieties of C. domesticus ', 

 C. aureus, G. anthus, G. latrans, G. antarcticus, C. magellanicus, 

 and G. cancrivorus have the characters of G. azaree. 



We are thus enabled to distinguish two series of Canidse, the one 

 of which may be termed Alopecoid and the other Thooid. 



The figures of the late Prof. Gervais, "Memoire sur les formes 

 cerebrales propres aux animaux carnivores" (Nouvelles Archives du 

 Museum, tome vi.), prove that the Thooid character of the brain 

 obtains in G. aureus, G. sime7isis, G. lupus, G. dingo, C. sumatrensis, 

 G. primcKvus, G. jubatus, and Lyeaon picttis ; while the Alopecoid 

 features are very obvious in the Fennec. 



4. But within each of these series there are considerable modifi- 

 cations, which give rise to corresponding terms in the two series. 



The first of these modifications appears in the proportion of the 

 sectorial and next following teeth relatively to the basicranial axis 

 (= 100), shown by the following table in six examples of the Alo- 

 pecoid series : — 



Table III. — Proportional Measurements of the Teeth in Alopecuids. 

 A. B. 



These measurements represent individual specimens ; and it must 

 be recollected that others might vary considerably on either side of 

 the proportions here given. But they suffice to prove, firstly, that in 

 the group A the sectorial teeth are relatively smaller than in the group 

 B, so that it may be convenient to speak of the one as microdont 

 and the other as macrodont Alopecoids ; secondly, while 2^, — , 

 ,;^, and ;^p2 ^ become larger between G. zerda and G. argentatus^ 

 the increase is far greater on the part of ^^^ than on that of — , 

 and of '— than on that of "-^. Thirdly, while in G. zerda '-^ is 

 to ^^^ as 1 : 1-19 and ^^^, to ^^ as 1 : 1*71, in G. argentatus 

 the former proportion is 1 : 1-39 and the latter as 1 : 2-26. In 



' lu a skull of a Blenheim Spaniel the frontal sinuses are totally absent, but 

 the disposition of the orbito-froutal ridge is exactly as in other domestic Dogs. 

 I do not know whether this peculiaritj* is general in the Blenheim breed or not. 



