The Sea Butterflies 



after dusk, but were rarely seen in daytime, or after ten o'clock 

 at night. In the aquarium they crept along the bottom by 

 means of their wing-like appendages. In daytime they would 

 rise a few inches, then fold their wings and drop. But by night 

 they came up and gambolled at and near the surface, flapping 

 rapidly about like butterflies. 



Whales swallow enormous numbers of pteropods of the 

 genera Limacina and Clio, which swarm at twlight, in Arctic 

 seas, colouring the surface for miles. 



Genus CARINARIA, Lam. 



Shell cap-shaped, thin, glassy, brittle, covering the stalked 

 nucleus; body large, oblong, gelatinous, with two fins, a well- 

 developed head, eyes, tentacles and a strong snout with toothed 

 tongue. The gills, which protrude from under the shell, are 

 feathered. 



The shells of these strange ocean swimmers were known 

 long before the animals had been observed. One of them looks 

 like the cap of some fairy harlequin; the peak surely ought to 

 dangle a tassel of spun glass. Unnecessary seems the shell indeed, 

 as the creature darts about, seizing small pelagic animals with its 

 great proboscis. 



C. Atlantica, Ads. and Rve., inhabits the North Atlantic. 

 The shell is depressed and the apex decidedly coiled. Similar 

 to it is the Mediterranean species, C. jragilis, Bory. 



C. vitrea, Lam., larger, and with shell attenuated to a high, 

 sharp peak, is found in the Indian Ocean. 



Genus ATLANTA, Les. 



Shell nautiloid, minute, glassy, compressed, keeled; aperture 

 small, notched; operculum lamellar; animal able to withdraw into 

 shell; gills contained in a dorsal mantle cavity; head large; eyes 

 conspicuous; ventral fin fan-like, provided with a fringed sucker. 



A. turriculata, d'Orb., is a lively little mollusk. It swims, 

 shell downward, with sudden jerks, by means of the fin-like foot, 

 and the tail fin. It rests when tired by attaching the disk to 

 floating objects. "Glassy Nautilus" it was called before the 

 structure of the soft parts was known. 



Habitat. — Warm parts of the .A.tlantic Ocean. 



242 



