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Show 248 PROF. HUXLEY ON THE CRANIAL AND [Apr. 6, groups, in one of which the peculiarities of Canis vulpes, while in the other those of C. azarce are always to be met with. Similar to C. vulpes are C. fulvus, G. argentatus, C. cinereo-argentatus, C. littoralis, C. niloticus, C. caama, G. zerda, C. lago-pus ; and, on the other hand, C. lupus, all varieties of G. domesticus \ G. aureus, G. anthus, G. latrans, G. antarcticus, G. magellanicus, and C. cancrivorus have the characters of G. azaree. W e are thus enabled to distinguish two series of Canidae, the one of which may be termed Alopecoid and the other Thooid. The figures of the late Prof. Gervais, "Memoire sur les formes cercbrales propres aux animaux carnivores" (Nouvelles Archives du Museum, tome vi.), prove that the Thooid character of the brain obtains in G. aureus, 0. simensis, C. lupus, G. dingo, C. sumatrensis, G. primcevus, G. jubatus, and Lycaon pictus; wbile the Alopecoid features are very obvious in the Fennec. 4. But within each of these series there are considerable modifications, 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 Alopecoid series:- T A B L E III.-Proportional Measurements of the Teeth in Alopecoids. 1. Length C. zerda. of pm. 4 20.g W^..17*3 ^ • * 2 4 * ,-2 * * I* A. 2 C. littoralis. 22*4 18*1 27*2 15*7 3. C. famc-licus. 23*5 18* 28* 13*5 4. C. vulpes. 27*3 19*4 30*5 14*7 B. 5. C. niloticus. 28*3 19-4 31*1 14*4 6. C. argentatus. 28*5 20*5 34-4 15*0 1:6 1 : 1*38 1: 1*18 1 : 1*43 1 :107 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 m ay be convenient to speak of the one as microdont and the other as macrodont Alopecoids; secondly, while ?HhAt ?h±} - [ , and -2 all become larger between C. zerda and G. argentatus, the increase is far greater on the part of p-^- than on that of - , and of 2*-! than on that of m-^. Thirdly, while in G. zerda ^ is to ^ ^ as 1 : 1*19 and - 2 to - , as 1 : 1*71, in G. argentatus the former proportion is 1 : 1*39 and the latter as 1 : 2*26. In 1 In a skull of a Blenheim Spaniel the frontal sinuses are totally absent, but the disposition of the orbito-frontal ridge is exactly as in other domestic Dogs. I do not know whether this peculiarity is general in the Blenheim breed or not. |