222 



1154. The right scapula of the same Auk. It is narrower in proportion to its 

 length than in the Penguin. Hunterian. 



1155. The right coracoid of the same Auk. 



The clavicular process is long, strong, and curved j the scapular process compressed, trian- 

 gular, and perforated at its base. 



Hunterian. 



1156. The right femur of the same Auk. Hunterian. 



1157. The right tibia of the same Auk. The procnemial and ectocnemial processes 

 are united by an oblique epicnemial ridge. Hunterian. 



1158. The left femur, longitudinally bisected, of the same Auk : it shows a medul- 

 lary cavity. Hunterian. 



1159. The left tibia, longitudinally bisected, of the same Auk: it, also, has a me- 

 dullary cavity. Hunterian. 



1160. The right metatarsus of the same Auk. Hunterian. 



Genus Fratercula. 



1 161. The skeleton of the common Puffin (Fratercula arcticd). 



The superorhital ridge is remarkable for the short extent of its attachment to the frontals, 

 and for the development of its angles into the postfrontal and antorbital processes. The 

 superorbital glandular fossa meets the temporal fossa on the upper part of the ridge : the 

 rostral part of the premaxillary commences by an abrupt elevation above the nasal process of 

 the same bone, and the symphysial part of the mandible sinks down in an analogous manner 

 below the level of the rami, both forming the basis of a deep, compressed, sharp-pointed beak, 

 trenchant above and below. The vertebral and sternal ribs progressively elongate as they are 

 placed further back, and join each other at acute angles, as in the genus Aha and other 

 diving birds : the hypapophyses of the middle dorsal vertebra are remarkable for their great 

 length and terminal bifurcation. There are 21 vertebrae between the skull and sacrum, the 

 last seven supporting moveable ribs, of which the first pair is free, and the succeeding six 

 pairs articulated to the sternum by bony haemapophyses ; the eighth pair of ribs is attached 

 to the first sacral vertebra. There are 8 caudal vertebrae. 



Mus. South. 



