REPORT ON THE SPHENISCID^. 45 



bones are provided with pulley-like articular surfaces adapted to tlie basal extremities of 

 the first row of phalanges. 



The upper end of the common metatarsal mass is provided with two articular facets. 

 Of these the inner is oval, the outer quadrilateral in form. They articulate with the 

 condyles of the tibia. The posterior border of the upper extremity of the bone behind 

 these surfaces develops two well-marked calcaneal tubercles between which is a shallow 

 groove in which the tendons of the flexor muscles of the toes are accommodated. 



I have observed the following distinctive features in the metatarsus of different 

 genera of Penguins. 



In every species of Eudyptes the bone agrees with the description just given of that 

 of Eudi/ptes chrysocome from Tristan d'Acunha. In all the members of this genus which 

 I have examined, the proximal ends of the intermetatarsal grooves are perforated above, 

 so that there are two foramina, one between the second and third, and the other between 

 the third and fourth metatarsal bones, both of which appear on the posterior surface 

 of the bone. In all of them there are two calcaneal tubercles, and in all of them the 

 lower end of the second diverges from that of the third metatarsal bone. 



In Aptenodytes (PI. VII. fig. 14), as in Eudyp)tes, there are two intermetatarsal 

 foramina, and two calcaneal tubercles, but the lower end of the second does not diverge 

 from that of the third metatarsal bone to the same extent as in Eudyptes, these two 

 bones being nearly parallel with one another from end to end. Consequently, in 

 Aptenodytes the metatarsus is of nearly the same breadth at the upper and lower ends, 

 whereas in Eudyptes the lower exceeds the upper end in breadth. 



Pygosceles (PI. VII. fig. 13) closely resembles Aptenodytes in the parallelism of the 

 three metatarsal bones, but differs from that genus as well as from Eudyptes, inasmuch 

 as the intermetatarsal grooves are much less pronounced, and the separate elements of 

 the compound metatarsus are more completely anchylosed in it than in these genera. In 

 Pygosceles there are two intermetatarsal foramina, and in Pygosceles tceniatus, as in every 

 species examined, there are two calcaneal tubercles. 



Spheniscus (PI. VII. fig. 12), on the other hand, differs from all the other genera, 

 inasmuch as in every species of that genus the separate metatarsal bones are less com- 

 pletely fused together. In the members of this the intermetatarsal grooves are much 

 more forcibly pronounced than in those of any other genus, and form deep hollows, which 

 nearly separate the component elements of the metatarsus from one another. In 

 Spheniscus, moreover, the separate metatarsal bones are relatively considerably longer 

 and more slender than in any other genus. They are also more nearly parallel with one 

 another from end to end than in Eudyptes, but less so than in either Pygosceles or 

 Aptenodytes. In every species of Spheniscus there are two calcaneal tubercles. 



In Spheniscus demersus, Spheniscus mendiculus, and Spheniscus minor the external 

 intermetatarsal foramen is alone pervious. In these species the internal foramen is clearly 



