LARID^. — LXIII. 153 



10. HYDROCHELIDON, Boie. Black Terxs. 

 1. H. nigra, (L.) Stejii. Black Tern. Head, 

 neck and under parts black (in full plumage); wings 

 and tail above plumbeous like the back; crissum white; 

 small; L. 10; W. 8 to 9; T. 3^-. N. Am., chiefly inland. 

 [//. fasi2)es^ (L.) Gray.] 



2. H. /ewco/?fera,(Meisn.)WHiTE-WiNGED Black Tern. 

 Winn's whitenino; alona; border of fore -arm; tail and 

 upper tail coverts white. Straggler from Europe, a 

 single specimen lately taken on Lake Koshkonong. 

 iJLudomc Kumlien^ \H. leucoptera., (Meisn.) Boie.] 



//. RHYNCHOPS, Linnfcus. Skimmers. 



1. R. nigra, L. Black Swimmer. Cutwater. Glossy 

 black; white below; lower mandible about an inch 

 longest, compressed like a knife - blade, obtuse at end; 

 L. 16 to 20; W. 15; T. 5, sharply forked. Coast, 

 abundant southward. 



ORDER S.-PYGOPODES. 



{The Diving Birds.) 

 Feet palmate or lobate; tibiae feathered, buried in the 

 skin nearly to the heel joint, hence the legs are set very 

 far back, and the birds are scarcely able to walk at all 

 on land; hind toe small, elevated, often wanting. Nos- 

 trils developed; bill of various forms, horny, not lamellate 

 nor serrate; no gular pouch. Wings very short, scarcely 

 reaching the base of the very small or rudimentary tail. 

 Swimmers, many of them noted for their powers of div- 

 ing. We here omit the three -toed family of Alcid^e, 

 the Auks, they being strictly maritime and mostly 

 northern. The twenty -one known species all occur in 

 America. 



