THE GREAT BLACK-BACKED GULL. 
67 
Bides 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 
28 half rings. 
FAMILY XLIII.— PRO CELLARING. 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 ; coeca rather long ; cloaca oblong or globular. Trachea 
simple, with a single pair of inferior laryngeal muscles. 
