Shufeldt: Osteology of Lasiopyga and Callithrix. 71 



fourteenth or fifteenth caudal. This is also the fate of the outstanding 

 processes, each vertebia, as we approach the end of the tail, becoming 

 more rod-like and longer with enlarged extremities, and rudimentary 

 in character with diminished calibre to and including the tenth, after 

 which they progressively shorten again and become shorter and shorter 

 to the end of the appendage, the last ten or twelve being merely 

 rudimentary little rodlets, the terminal caudal being only 5 mm. 

 long as compared with the seventh, for example, which has a length 

 of 35 mm. 



The characters of the caudal vertebrae in Callithrix in many ways 

 resemble those of Lasiopyga, though the chevron-bones are more 

 rudimentary and the apophyses in the anterior caudals not so con- 

 spicuous. Only the first four caudals in Lasiopyga have the neural 

 canal a closed tube, though it may exist in the fifth, where its calibre 

 becomes of mere hair-like proportions. It is better marked in the 

 fifth caudal of L. griseoviridis, in which species the fifth caudal more 

 closely resembles the third, which is not the case in L. callitrichus. 

 Callithrix has its few anterior caudals much flattened out from above 

 downwards Mivart noted that "Chevron-bones and processes for 

 their attachment are altogether wanting only in the Simiincs and in 

 Macacus inuus. They attain their maximum in A teles, where they 

 present almost every variety of development in one or other part of 

 the caudal region." 



In those monkeys having prehensile tails, as in Ateles for example, 

 the processes of the caudal vertebrae are exceptionally well-developed 

 in order to afford attachment for the caudal muscles employed in the 

 grasping power of the appendage in this genus; and it is a well known 

 fact that all the vertebrae in these animals vary considerably through- 

 out the group. 



The Appendicular Skeleton. 

 The Fore Limb. (Plate XX, fig. 23). 

 In his excellent article "Ape" in the Encydopcedia Britannica, 

 Professor Mivart has given us the proportions of bones, particu- 

 larly the long bones of the skeletons of a great many of the 

 representatives of the group here under consideration. This has 

 been done so fully that it obviates the necessity of touching upon 

 this part of the subject in the present contribution, as the space 

 can be better utilized for presenting the description of the actual 



