STEGAyOPODES. 73 



Order STEGANOPODES.— The Totipal- 

 .MATE Swimmers. (Page i.) 



Families. 



'. Nostrils distinct ; lateral toes nearly equal, and nearly as long as the middle 

 one ; whole head feathered. 



Bill conical, compressed, pointed, without terminal hook, or unguis ; 

 ciilmen curved ; edge of upper mandible very concave ; tail short, gradu- 

 ated, the middle pair of leathers, in adults, very narrow and greatly 



elongated Phaethontidae. (Page 73.) 



'. Nostrils not perceptible ; lateral toes unequal, and one or the other of them 

 much shorter than the middle one ; head partly naked. 

 6'. Bill conical, the tip of the upper mandible without distinct hook, or 

 unguis. 

 c". Bill very thick through the base, the tip slightly curved ; tail about 

 half as long as the wing, graduated or cuneate, the feathers narrow- 

 ing toward the rather pointed tips Sulidae. (Page 74.) 



c*. Bill slender, the outlines (culmen especially) nearly straight ; head 

 very small, the neck extremely long and slender ; tail nearly as long 

 as the wing, rounded (fan-shaped when spread), the feathers very 

 broad, the middle pair transversely corrugated in the adult. 



Anhingidae. (Page 76.) 

 6'. Upper mandible terminated by a distinct hook, or unguis. 



c'. Tarsus moderately lengthened, much longer than the hind toe, including 

 its claw. 

 d'. Bill shorter than middle toe, compressed ; gular sac small, scarcely 

 distensible ; outer toe much longer than middle. 



Phalacrocoracidae. (Page 77.) 

 cP. Bill much longer than middle toe, much flattened ; gular pouch very 

 large, and greatly distensible; outer toe shorter than middle. 



Pelecanidae. (Page 81.) 

 c*. Tarsus excessively short, hardly equalling the hind toe (including its 

 claw) in length. 



Wings and tail cxcessivelj' lengthened, the latter deeply forked ; 

 middle toe much longer than the outer, its claw flattened and 

 fringed on inner edge; webs verj- small, occupying less than 

 half the space between the toes Fregatidse. (Page 82.) 



Family PHAETHONTID^.— The Tropic Birds. (Page 73.) 



Genera. 



(Characters same as those of the Family) Phaethon. (Page 74.) 



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