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Show 106 DR. ST. G. MIVART O N [Mar. 18, vice versa, I cannot but look with much scepticism on the specific distinctness of these forms. Burmeister describes (' Fauna Brasiliens,' p. 37, pis. xxiii., xxviii., and xxix.) a specimen in his possession which he regards as identical with the C. vetulus of Lund, which species he (as before said) also identifies with the C. azarce of Wied. But his description and his plates show that an important distinction exists between what he calls C. vetulus and both the C. vetulus of Lund, and Wied's and Waterhouse's C. azarce ; for its fourth upper premolar is extremely small, while the two upper molars are relatively very large. He also gives their dimensions (' Reise durch La Plata,' p. 407) as follows :- Length of 1^4=9 ; length of M. 14- M. 2 = 14, or as 100 to 155. But Lund gives an apparently careful and accurate figure of the skull of his C. vetulus, the type of the species, and this shows a well-developed fourth premolar and a small molar, which teeth bear to each other the proportions of 100 to 130. Now my experience is that though the proportions of the teeth are not constant, they yet afford better characters than do variations of tint in the fur-a condition often variable with the season. I do not think that the C. vetulus oi Burmeister can be the same as the C. vetulus of Lund ; and if it is not, it must be distinguished by some other appellation. As to what the latter may be, Burmeister identifies it with the C. azarce of Wied, and therefore he ought not to call it C. vetulus, but what he regards as its original denomination, C. azarce ; and this, for all we can see, it may be, and I am disposed to think that it is a pale variety of it, judging from Lund's representation of its external form. Now in the British Museum there are two skins and three skullsl from Brazil, which appear to me to belong to the same species as that described by Burmeister under the name C. vetulus. Its external characters fairly correspond with those of Burmeister's form, but its dentition appears to m e to weigh heavily in favour of their specific identity. I find the IV* to be '7, and M. 1-f-M. 2 to be 1*20 in two skulls, and in the remaining one, P- 4 is -75 and M. 1+M. 2 is T15. The average of the three is therefore 7'1 and 1*18, or as 100 to 166. It is interesting to note that the three skulls referred to differ amongst themselves in the form and development of the sagittal elevation and in the shape and proportions of the frontal postorbital processes. As to Lund's C.fulvicaudus, Burmeister remarks (' Fauna Brasiliens,' p. 40) that it seems to be very near Lund's C. vetulus, but is distinguished by its smaller stature, blunter head, and proportionally stronger build, clearer and more yellow ground tint, and rusty tail with black end, ochre-coloured patch behind the ear2; finally the front of the arms and the hind legs, above the knees, are darker. 1 Nos. 821 A, 821 B, and 821c. The first of these is extracted from No. 44. 3. 7.3. 2 The mounted skin of C. vetulus in the British Museum has an ochre patch behind the ear, but has not the characters otherwise attributed to C. fulvicaudus. |