Alcid^;.] 



OSTEOLOGIA AVIUM. 



[Sphenicin^e. 



Spheniscus, Briss. 



Minor, Forst. 



Cranium large, strong, with the upper edges of the orbits much depressed, and 

 roughened space between the orbits rather narrow ; orbital septum with one large 

 foramen, the post orbital processes pointing downwards, blunt at the extremities ; 

 occipital bone with the ridges prolonged into a projecting keel; occipital protuberance very 

 large. Palatine bones very broad, sloped at their posterior outer edges towards the 

 interarticular bones, and gradually narrowed anteriorly; interarticular bones battle- 

 dore shaped, with the broad end placed towards the palatine bones. 



Sternum long, without any xiphisternal process, with a large elongated fissure on 

 the posterior margin on each side of the keel, the strip of bone bounding them on their 

 outward edges widened and turned inwards posteriorly, the central portion of the 

 sternum between the fissures not so long as the strip; keel with the lower edge nearly 

 straight, anterior edge slightly curved, the point projecting beyond the anterior edge of 

 the horizontal portion of the sternum ; manubrial process well marked. 



Pelvis very similar in shape to Alca torda, but with os pubis not so much prolonged, 

 and the spines projecting on each side of the ilium not so long. 



Ribs with the styliform process long, broader at their hinder extremities than at 

 their junction with the ribs. 



Furculum broadest near its junction with the coracoids, and gradually narrowed to 

 the junction of the rami, where there is a slight process projecting backwards. 



Coracoids of moderate strength. 



Scapula shaped very much like a shoulder of mutton, with the small end towards 

 the coracoids, which is not above one-fourth the width of the hinder end, the edges 

 much curved, the hinder edge truncate. 



Wing-hones much flattened ; very similar to Alca impensis. 



Leg-bones with the metatarsus very short ; fibula strong, extending down the side of 

 the tibia for three-fourths of its length, the proximal end of the tibia not elongated, as 

 among the Colymbidce ; metatarsal bones much flattened. 



Measurements. 



Tenths. 



Length of humerus 18 



Length of ulna 13 



Length of metacarpus 11 



Length of femur 18 



Length of tibia 29 



Length of metatarsus 12 



Length of sternum 31 



216 



Tenths, 



Breadth of posterior margin of sternum 15 

 Breadth of anterior margin of sternum 1 6 



Depth of keel 8 



Length of head 39 



Breadth of head 16 



Length of pelvis 35 



Breadth of pelvis 14 



