OF ORNITHOLOGY 129 



difference in the general gull-like appearance of the different 

 members of the different sub-families, though some of them 

 display more agility of wing than others. The larger birds 

 have an apparently slower and steadier motion while on the 

 wing than the smaller species, yet this may not be strictly 

 true — their larger size may only make it seem true. All the 

 members of the family are remarkable for their habit of div- 

 ing, from high in the air, for their prey, and will often remain 

 entirely submerged for several seconds at a time ; yet, as a 

 rule, they are not diving birds. Their bodies are extremely 

 bouyant while they rest upon the water, and they swim with 

 ease, grace, and facility. They are more or less gregarious, 

 often flying together in flocks of many hundreds or even thou- 

 sands. All their motions are full of grace, and even their 

 walk has a sort of daintiness about it that makes it appear 

 not altogether awkward. Although the sea and seacoast are 

 their places of greatest resort they are not confined there alto- 

 gether, and many species follow up the larger streams and 

 even occur far inland about lakes and ponds and other large 

 bodies of water. They are distinguished from their near al- 

 lies the Petrels by the absence of the tubular nostrils, for which 

 the former are noted. There is no gular sac. The bill is long 

 and dart like. The toes well webbed ; hind toe short, ele- 

 vated, and free. The general color white or pearl-gray (blu- 

 ish). In general appearance not unlike a Sea Dove. 



Professor Baird gives the following brief diagnosis of the 

 four Sub-families of this FAMiiiY : 



" Lestridin.e. — Basal half of upper jaw with a horny cov- 

 ering, distinct from the tij), and under which the nos- 

 trils open considerably beyond the middle of the bill. 

 Bill abruptly and much decurved at the tip. Tail cu- 

 neate. Body full, stout. 

 Laein.e. — Covering of the bill continuous. Anterior 

 extremity of nostrils generally reaching to the middle 

 of the bill. Culmen generally decurved towards the 

 tip. Body robust. Tail generally even. 



