Shufeldt: Osteology of Lasiopyga and Callithrix. 79 



Metatarsus and Phalanges. All of the metatarsal and phalangeal 

 bones, save the terminal joints, are considerably curved, the concavity 

 being pal mad. This is most evident in Lasiopyga callitrichus; rather 

 less in L. griseoviridis, and least of all in Callithrix. In the marmoset, 

 as in its hand, the terminal joints of the pes are laterally compressed, 

 much curved, and pointed. In Lasiopyga it is the third metatarsal 

 which is the longest bone of the tarsus and possesses the biggest shaft; 

 while in Callithrix the fourth metatarsal is a shade longer than the 

 third, and its shaft is about equal in caliber with it. In proportion 

 to the size of the animal, the marmoset possesses a long and narrow 

 foot, its slender tarsal bones and toe-joints exhibiting but little curva- 

 ture, are when articulated almost parallel to each other, and to this 

 the hallux forms no exception. 



Closing Remarks. 



This paper has aimed especially to point out the main skeletal 

 differences, especially in the skull and axial skeleton, which may 

 exist between two species of apes which have been placed in the same 

 genus, viz., Lasiopyga callitrichus and L. griseoviridis. It also essays 

 to clear up faulty records and illustrations of previous writers, particu- 

 larly in the matter of the correct number of vertebrae in various divi- 

 sions of the spinal column. It gives in detail the osteology of Calli- 

 thrix. The illustrative plates should possess value, and should 

 especially prove to be of assistance to those engaged in the study of 

 the craniology of this group. 



In the first volume of "A Review of the Primates" Dr. Elliot gives 

 considerable information concerning the "Bald-headed Tamarins" 

 of the genus Seniocehus. They are placed by him in Family I of 

 Suborder 2 of the Anthropoidea, and three species are described, viz.: 

 S. hicolor, S. meticulosus, and 5". martinsi. Their dental formula is 



2—2 I-I 'K-'K 2-2 



given thus: I. ; C. ; P. ^^-^; M. = 32. 



2-2 i-i 3-3 2-2 



The literature relating to this genus and the marmosets, covering 

 the eaily wiitings of Linnaeus (1758) to date, is quite extensive. 



Elliot places the tamarins in the four genera Seniocebus, Cerco- 

 pithecus, Leontocehiis, and GEdipomidas. Formerly they were ai raj'ed 

 with the marmosets either in the genus Hapale or in Callithrix. 



"The chief difference between members of Callithrix," says Elliott, 

 "and the species now under consideration [Seniocebus] is found in the 



