Laridje.] osteologia avium. [Larinje. 



Diomedia, Linn. 



Fuliginosa, Gm. 



I have a sternum of this bird, sternal apparatus, and pelvis. The distinction is in 

 the form of the posterior margin of the sternum, which is scolloped out for its whole 

 width. I have also the skeleton of D. melanophrys, which is similar. 



Larus, Linn. 



Ridibundus, Linn. 



Cranium with a deep indentation upon each orbit, and a narrow ridge between them ; 

 masseter impression very distinct ; occipital bone slightly projecting on each side in the 

 form of a blunt spine, pointing forwards ; post orbital processes narrow, pointing 

 downwards and backwards. Palatine bones narrow, the outer edges recurved for 

 about half of their length, sloped backwards from the broadest part to the inter- 

 articular bones, which are rounded, and have a slight keel on their upper edge, 

 broadest anteriorly ; orbital septum with one foramen. 



Sternum of moderate length and breadth, with two fissures on each side of the keel, 

 the inner one largest; keel rather broad, arched on its inferior edge, anterior edge 

 scolloped out, with the point projecting. Manubrial process flattened perpendicularly, 

 upper portion thicker than the lower. 



Pelvis similar to the Procellarince, but with the os pubis projecting further backward. 



Ribs slender, with very long styliform or pleural processes. 



Furculum much arched on its anterior aspect, transversely flattened ; a small 

 flattened process, pointing backwards, at the junction of the rami. 



Coracoids of moderate size and length. 



Scapula light, and of the same breadth until very near the hinder extremity, where 

 it is slightly widened, and afterwards sloped off to a blunt point. 



Wing-bones with the ulna longer than the humerus ; thumb one-third the length of 

 the metatarsus. 



Leg-bones. Metatarsus with a groove down the front ; calx small, a slight splint 

 proceeds from it a short distance down the back of the metatarsus. 



Measurements. 



Tenths. 



Length of humerus 36 



Length of ulna 41 



Length of metacarpus 22 



Length of femur 17 



Length of tibia 33 



Length of metatarsus 19 



Length of sternum 24 



Tenths. 



Breadth of posterior margin of sternum 12 

 Breadth of anterior margin of sternum 12 



Depth of keel 7 



Length of head 35 



Breadth of head 14 



Length of pelvis 28 



Breadth of pelvis 14 



2r 225 



