404 OSTEOLOGY OF THE PENGUINS. 



'ambiens' muscle. The inner surface of the bone is smooth. 

 The upper end of the patella is obhquely truncated, and affords 

 insertion to the muscular fibres of the extensor cruris muscle, 

 while the lower end, narrower and more irregular in form, i& 

 attached by means of very short ligamentous fibres to the anterior 

 border of the upper end of the tibia. The patella presents essen- 

 tially the same characters in every species." This description 

 answers very well for Apte7iodytes,oiilythis latter Penguin has the 

 patella much larger, as will be seen iu the figure. In the great 

 majority of birds where a patella exists it is found to have the 

 form of an oblate hemispheroid, with its base directed upwards 

 for insertion of the extensor cruris. 



Other characters are the long and stout Jihda, and the re- 

 markable skeleton of pes. In this latter the iarso-metatarsus is 

 short, broad, and of an oblong outline, the three metatarsals 

 composing it being more or less distinct, lying parallel to each 

 other in the horizontal plane, being thoroughly fused together 

 at their extremities. The hallux is greatly aborted in most 

 species, and plays no important part in the foot of any of the 

 Penguins. 



The phalangeal formula of the joints is normal, and the three 

 anterior toes are cylindrical in form, with closely locked articu- 

 lations, and terminate with strong, little-curved claws. This 

 part of the skeleton of the foot has a very reptilian aspect ; and 

 I find in ApteQiodytes pennantii three smallish sesamoids in its sole, 

 and others still smaller under the podal digits at their bases. 



The characters of the scapulse, the skeleton of the pectoral 

 limbs, the patellae, and the feet exhibited on the part of the 

 Penguins are not to be found in any other existing group of 

 birds, and it would seem are alone sufficient to warrant us in 

 placing these remarkable pelagic forms in a suborder of birds 

 by themselves. This, as already stated above, has accordingly 

 been done. 



EXPLANATION OF PLATE XXXVIIL 



Right lateral view of the skeleton Sphnmnis demer^us. 



Considerably reduced. From a photograph of the specimen in the 

 collection of the U.S. National Museum at Washington (No. 17,938). 

 Specimen collected at Angra Pequena, South Africa. 



