68 Annals of the Carnegie Museum. 



twenty-eight caudal vertebrae. In only one species of Lasiopyga 

 ( Cercopithecus) did Flower find twenty-eight caudals, and that in L. 

 patas. 



Now coming to Callithrix jacchus (Hapale), of which I have two 

 skeletons, I find in one seven cervicals, thirteen thoracics or dorsals, 

 six lumbars, three sacrals, and twenty-eight caudals, the distal caudal 

 being less than 2 mm. long and as fine as a human hair. This agrees 

 with Flower, except as to the caudal vertebrae, of which he records 

 only twenty-three, or six less than I find in a perfect specimen. 

 Owen states in his Anatomy of Vertebrates that "Nineteen is the 

 usual numbei of dorso-lumbar vertebrae in the Platyrrhine group, the 

 Spider-monkeys (Ateles) ofifering the exception of eighteen, viz: D. 14, 

 L. 4." This agrees with my count above. Owen also states that in 

 most Platyirhines the number of caudal vertebrae are usually thirty 

 or upwards, "Ateles paniscus having thirty-three caudals." This 

 is entirely at variance with what we find in the table given by Flower. 

 Mivart states that "The dorsal vertebrae vary in number from eleven, 

 as sometimes in Cercopithecus [Lasiopyga] and Macacus, to fourteen, 

 as sometimes in Hylobates, 01 even to fifteen, as in Nyctipithecus 

 [Aotusy So fai as Lasiopyga goes, this is not only different from 

 Flower's count for five different species of Lasiopyga {Cercopithecus), 

 but it is evidently incorrect. But this is only one instance out of 

 many where these two eminent anatomists disagree with respect to 

 the number of vertebrae found in the several divisions of the spinal 

 column of the Primates. We are dealing here, however, only with 

 Lasiopyga and Callithrix. 



In the atlas of both these genera of apes there are two foramina, on 

 either side, one above and one below the transverse process, for the 

 passage of vessels. They lead to a common opening, which is found 

 just posterior to the superior articular surface for the occipital condyle. 

 It is for the passage of the vertebral artery, on either side; but exactly 

 in what manner the branching takes place I shall be unable to state, 

 until an opportunity occurs to dissect another specimen in the flesh. 

 In man the foramen for the vertebral artery is single on each side. 

 The vertebral vein may upon quitting the cranium pass through the 

 other foramen. Owen seemed to believe that both perforations were 

 for the vertebral artery in the marmoset ( Hapale jacchus) when he 

 stated that in that species "The transverse process of the atlas is 

 perforated lengthwise and vertically by the vertebral artery, and the 



