184 THE GREAT BLACK-BACKED GULL. 



sides of the thyroid bone in front, separating from the trachea, attaching 

 themselves to the subcutaneous cellular tissue, and inserted into the furcula. 

 Another pair arise from the same bone in front, spreading over the whole 

 anterior surface of the trachea, then become collected on the sides, send off 

 a slip to the costal process of the sternum, and continue narrow, to be 

 inserted into the last arched half-ring of the trachea; thus forming what is 

 called a single pair of inferior laryngeal muscles. Bronchi wide, each with 

 2S half rings. 



FAMILY XLIII.— PROCELLARINvE. FULMARS. 



Bill generally shorter than the head, moderately stout, compressed; upper 

 mandible with the ridge formed of two generally united plates, at the anterior 

 part of which, usually about half the length of the bill, are the nostrils; the 

 sides separated by a groove, the tip a decurved, compressed, pointed unguis; 

 lower mandible with the angle very long and narrow, the tip more or less 

 decurved. Head of moderate size, ovate; neck of moderate length; body 

 compact. Feet of ordinary length, rather slender; tibia bare below for a 

 short space; tarsus a little compressed, anteriorly scutellate; toes four, the first 

 extremely small and elevated, with a conical deflected claw; anterior toes 

 webbed; the third and fourth nearly equal. Claws arched, compressed, 

 acute. Plumage full, soft, rather compact above. Wings long, rather broad, 

 pointed, the first quill generally longest. Tail short, of from twelve to 

 sixteen feathers. (Esophagus very wide, often enormously dilated, espe- 

 cially at its lower part, stomach small, moderately muscular; intestine of 

 moderate length; cceca rather long; cloaca oblong or globular. Trachea 

 simple, with a single pair of inferior laryngeal muscles. 



