214 PROCEEDINGS OF THE ACADEMY OF 



Subfam. Larinie. — Covering of bill continuous: bill epignatbous. Tail 

 usually squarish ; rarely forked or wedged. Head never crested. Hallux in 

 one speciesimperfect. Tarsi almost alwayssmooth. Feetambulatorial. Genera: 

 Larus (possibly with a few divisions), Rissa, Pagophila, Chrcecocephalus, Rhodo- 

 stethia, Xenia^ Creagrus. 



The central group of the family : all the genera closely related. Distinct, 

 on the one hand, from Leslr/diiue, but on the other shading into S/erninie, 

 through the smaller, hooded, forked-tailed. &c , species, the bill of which in- 

 sensibly passes into the tern-like form. Altogether too many genera have 

 been invented, not discovered, in the genus Larus. I would unite under this 

 name all the large square-tailed, unhooded forms, of whatever color, doing 

 iivrixj with Blasipiis, Adelarus, &c,, not to mention a number of worthless 

 '• coups," as M. Temminck would justly call them. Rissa is dififeient in its 

 feet, at least in the type of the genus. Pagophild is well marked in several 

 respects; it correspond*' to Gygis among Terns, a.w\ Pugodroma among Petrels. 

 Chrcecocephalus may well embrace all the smaller square-tailed "hooded" 

 Gulls; these go into the tern-like shape of bill. The ottier genera above 

 named are based mainly upon shape of tail. 



Subfam. Sterninie. — Covering of bill continuous. Bill paragnatlious. 

 Wings extremely long and' pointed. Tail generally long ; commonly forked, 

 but of other shapes. Hallux constant. Tarsi smoothish ; feet small, scarcely 

 ambulatorial. Head often crested ; sometimes singularly so. Genera : 

 Gelochelidon, Thalasseus, Fhcetusa, Sterna, Ilydrochelidon, Haliplana, Anoiis, 

 Inca, Gygis. 



Adhering well to a recognizable type, but varying in details of form, whence 

 the numerous genera. GelocheUdon is gull-l\ke, especially iu bill. Thalasseus 

 comjjrises the largest robust species, with a soft, flowing occipital crest. 

 PhaUisa has large southern species with great turgid bill. Sterna is central, 

 wiih many deeplj'-forked tailed species like hirundo, &c. Ilydrochelidon is 

 singularly fissiped, from defect of webs. Haliplana is nearly Sterna, but with 

 different bill, feet and coloration. Anousis a singular form, with a long forked- 

 graduated tail ; i. e., central feathers shorter than next, others again graduated. 

 Inca comes near it, but has unique, curly plumes on the side of the head, as 

 in the Cormorants, and especially some Auks ! Gygis is the Tern expression 

 of the idea of the Gull Pagophila and the Petrel Pugodroma. The Terns are 

 marine Hirundinidx ! 



■ Subfam. Rhynchopince. — Bill cultrate, hypognathous ; otherwise as iu the 

 preceding subfamily. Genus Rhynchops. 



The single genus is a Tern in everything but the anomalous bill. The 

 light cancellated internal structure of the turgid part of the upper mandible 

 suggests that of Rhamphastidie. The Skimmers feed as whales do. 



Families of STEGANOPODES. 



This order contains no less than six families, none of which have more than 

 a single subfamily. Regard for equivalency of groups necessitates this view. 

 For if we institute two families, upon whatever basis, as some have done, we 

 shall find that their subfamilies are fully as different from each other as the 

 families are. Recognition of six families here, and only one with numerous 

 subfamilies among Lav.ellirostres, might not seem at first sight to be based 

 upon parity of reasoning. But I think the distinction is one with a differ- 

 ence ; and one too for which a good reason can be shown. S/eganopodcs are 

 compounded from other Natatores, that is, forms have been taken from other 

 orders, furnished with a pouch, wefebed hallux and abortive nostrils, and 

 otherwise modified to make up tliis order. Hence the dissimilar types, each 

 representing a family. This is not so with Anseres. I cannot find the centre 

 of Steganopodes ; the families seem all peripheral, looking towards other 

 groups. They show no tendency to merge into each other ; they represent 



[Dec. 



