PENGUINS. 



57 



FIG. 25. Pelvis of 

 Catarractes dem.fr- 

 sus, dorsal view. 



Spheniscida?," from which, on account of the importance of determining the rela- 

 tionship of the higher group of birds, we shall quote freely in the following. 



The vertebral column is characterized by the opisthoccelous character of the dor- 

 sal vertebra?, a character which, judging from the frequency of its occurrence in the 

 two groups, is more truly reptilian than avian, and by the mobility of 

 the dorsal vertebra? upon one another, and the absence, even in the 

 adult, of that complete anchylosis between the dorsal and lumbo- 

 saeral vertebra? on the one hand, and of the latter with the pelvic 

 bones on the other, which obtains in the majority of birds. The 

 opisthocoelous character of the vertebra? shows itself for the first time 

 in the third dorsal ; the cervical and the two first dorsal vertebra? being 

 saddle-shaped. The succeeding dorsals differ in having the ante- 

 rior surfaces rounded and globular, while their posterior surfaces are 

 deeply concave. The lumbo-sacral portion of the vertebral column 

 never becomes anchylosed with the pelvic bones, not even in the 

 adult (Fig. 25). The pubis does not coalesce with the ischium, ex- 

 cept where it enters the acetabulum. 



The uncinate processes of the ribs are exceptionally large, and 

 are only connected with the ribs by articulations, never becoming 

 anchylosed with them as in the majority of birds. 



The shoulder-blade (Fig. 26) is remarkable for its enormous size and its great 

 width posteriorly, and the coracoid bone for its great strength. The most characteris- 

 tic feature of the wing, as a whole, is perhaps the great amount of compression exhib- 

 ited by all its bones, offering, when the wing-paddle is 

 carried forward while swimming, the minimum resist- 

 ance to the surrounding water. Furthermore, the 

 movements permissible between the different bones are 

 much more limited than in other birds so much so 

 that flexion and extension in the joints beyond the FIG. 26. - Scapula of Caterracftw. 

 shoulder can scarcely be said to be possible. These articulations, however, admit of a 

 very considerable amount of rotation, converting the wing into a screw-like blade. The 

 wings are never used as oars, but are brought into use alternately. The metacarpal 

 consists of a single bone, which shows, however, the* three elements of which it is 

 composed. The first or radial metacarpal is destitute of any phalanx, and the pollex 

 is consequently absent; the second finger has two phalanges, and the third only one. 



The legs are less modified than the wings, but the tarso-metatarsus presents fea- 

 tures which serve at once to distinguish that bone from the corresponding skeletal 

 element of any other group of birds, being altogether shorter and 

 broader than in these, with the single exception of the genus Fregata. 

 From Fregata, however, as from all other birds, the penguin is dis- 

 tinguished by the clearly-defined separation of the metatarsal elements, 

 the shafts of which are differentiated from one another, while in other 

 birds these bones are indistinguishably fused together. Of the other 

 bones, only the patella is remarkable, it being very large and wedge- 

 shaped, with a greatly developed groove for the tendon of the ambiens 

 muscle. Four toes are always present, the hallux being directed forward. 



It has been suggested to me, Professor Watson further says, that the large devel- 

 opment of the cutaneous muscles in these birds is probably a means whereby water 



FIG. 27. Right 

 metatarsus of 

 Catarractes. 



