442 MR. R. I. POCOCK ON THE 



The AlisfJienoid Canal in Civets and Hyamas. 



Mr. R. I. PococK, F.R.S., F.L.S., F.Z.S., Curator of Mammals, 

 gave an exhibition, illustrated by lantern -slides, to show some 

 points connected with the alisphenoid canal in the Viverridfe * 

 and Hy£enida3, and remarked : — 



" As is well known, the alisphenoid canal is always absent in 

 the Felid^e (text-fig. 1, A). In the Yiverridaj, on the contrary, 

 it is nearly always present, although it is never found in the 

 Mascarene genera Galidia, Galidictis, and Salaaioia (text-fig. 1, B), 

 forming the subfamily Galidictinse, and may be present or absent 

 in Cynogale (Cynogalinas) and Eupleres (Euplerinfe), two aberrant 

 genera of Viverridte. By Mivart, Flower, and authors inspired 

 by them, it is also stated to be variable in its occurrence in 

 Viverricida, a genus closely related to Viverra and Genetta, in 

 which it is always present. 



" Examination of the skulls of Cynogale and Eupleres shows 

 conclusively that the absence of this canal, when it is absent, is 

 due to suppression, complete or partial, of its external bony wall. 

 Nevertheless, when this wall is unossified in these forms, the 

 channel marking the course of the external carotid artery is very 

 apparent. This bony wall is also so short in some Mongooses, 

 e. g. Crossarchiis, that a comparatively slight defect in ossification 

 would convert the canal into an open channel, such as is seen some- 

 times in Cynogale and Eupleres. In d'ossarchus (text-fig. 1, C, D), 

 Cynogale, and Euj^leres, moreover, the foramen rotundum opens 

 alongside the anterior orifice of the alisphenoid canal into the 

 posterior part of the temporal fossa close to the sphenoidal fissui'e 

 \foramen lacerum anijcum). In the Galidictinse the foramen 

 rotundum occupies precisely the same position with regard to 

 the sphenoidal fissure. This part of the skull in Galidictis, for 

 example, bears a close resemblance to that of Crossarchus, except 

 that there is no trace whatever of the alisphenoid canal. Never- 

 theless, the general likeness alluded to suggests that the absence 

 of the canal in Galidictis may be due to the complete suppression 

 of its outer wall (text-fig. 1, B). 



"This interpretation seems to be the one that is curiently 

 accepted ; and since no alternative has, so far as I am aware, 

 been suggested, it may be assumed that the same explaijation 

 has been tacitly extended to those specimens of Viverricida in 

 which the canal has been described as absent (text-fig. 1, E). The 

 statement, however, that the canal is absent in that genus is not 

 true. It is in reality present, its apparent absence being due to 

 the closure of its postei'ior orifice and not to the imj^erfection of 

 its outer wall. 



" Justification for this view rests upon the following facts : — 



" The orifice, lying alongside the sphenoidal fissure in Viver- 

 ricula, which Flower would doubtless have called the foramen 

 rotundum, is in reality the anterior end of the alisphenoid canal, 

 which, when complete, opens posteriorly by a small aperture just 



'^ * The term ViveiTidiie is liere used, vvitliout prejudice, in the sense in which 

 Flower and Mivart and their successors employed it. 



