225 
FAMILY XLII. — LARIN M. GULLS. 
Bill of moderate length, straight, compressed, acute ; upper mandible 
with the dorsal line generally straight until toward the end, when it is 
decurved, the ridge convex, the nasal groove rather long, the edges sharp, 
direct, overlapping, the tip rather acute and declinate ; lower mandible 
with the angle long and very narrow, the dorsal line ascending and nearly 
straight, with an angular prominence at its commencement. Nostrils sub- 
medial or basal, oblong. Head of moderate size, ovate ; neck of moderate 
length ; body rather stout. Legs short or of moderate length ; tibia bare 
at its lower part ; tarsus anteriorly scutellate ; toes four, the first very small, 
free, the third longest ; anterior toes connected by webs. Claws small, 
arched, compressed, rather acute. Plumage full, soft, blended, somewhat 
compact on the back and wings, the latter long and pointed ; tail of twelve 
feathers, even, rounded, or emarginate. Tongue long, slender, pointed ; 
oesophagus very wide ; stomach rather small, moderately muscular, with a 
dense, longitudinally rugous epithelium ; intestine of moderate length and 
width ; coeca small ; cloaca globular. Trachea simple, with a single pair 
of inferior laryngeal muscles. Nest on the ground, rudely constructed. 
Eggs few, not exceeding four, spotted. Young covered with down. 
Genus I.— RHYN CHOPS, Linn. SKIMMER. 
Bill longer than the head, nearly straight, tetragonal at the base, suddenly 
extremely compressed and continuing so to the end ; upper mandible much 
shorter than the lower, its ridge sharp, the sides erect but a little convex, 
the edges approximated so as to leave merely a very narrow groove between 
them, the tip a little rounded, when viewed laterally ; nasal groove rather 
short, near the margin ; lower mandible with the angle extremely short, the 
dorsal line straight or slightly decurved, the sides erect, obliquely grooved, 
the edges united into a very thin blade, which fits into the narrow groove of 
the upper mandible, the tip rounded or abrupt, when viewed laterally. 
Nostrils linear-oblong. Head rather large, oblong, considerably elevated in 
Vol. VIL— 29 
