416 
THE OCEAN WORLD. 
Fig. 237. Janthiim communis 
(Lamarck). 
The attention of naturalists has long been directed to a curious 
mollusc known under the name of Janthina communis (Fig. 237)! 
its body is globular, and it presents an opening 
in front without contracting itself in order to 
form the head, which is long and trumpet' 
shaped, terminating in a large buccal opening’ 
furnished with homy plates, and covered with 
little hooks ; and two conical tentacles, slightly 
contracted, but very distinct, each bearing at then' 
external base a long peduncle. The foot jS 
short, oval, divided into two parts : the anterior, concave and cup" 
shaped ; the posterior, flat and fleshy. It is this foot which hears 
a vesiculous mass like foam, which gives its peculiar character to the 
pretty mollusc. The mass consists of a great number of snaa^ 
bladders, which combine to keep the animal on the surface of tb e 
water. The shell is light, transparent, violet-coloured, and very 
much resembles the shell of the Helix. The Janthinas inhabit the 
deep sea, and often form hanks of many leagues in extent. Messrs- 
Quoy and (milliard have seen legions of Janthinas driven by 
current. They have sailed during many days through these wander* 
ing tribes, which would be the sport of every gale if they could Q°*’ 
by drawing their heads within their shells and contracting the 11 
natatorial vesicles, diminish their volume and increase their weight ft* 
will, so as to sink quietly to the bottom of the water till the temp eS * 
was over. It is even pretended that at the approach of danger (h e 
Janthina discharges a liquid of a dark violet colour, which disturb 3 
the water, and permits it to escape from its enemy. 
Buccranm 
This family includes a vast number of molluscs almost exclusive^ 
marine, among which are the beautiful genera Conus, Porcelain 1 ’ 
Almea, Cassis, and Murex, which we propose to pass in review. 
The genus Conus is especially rich in species, as well as numero 11 
in individuals. They are much sought after by collectors, being ve • 
rare, and command high prices. The shells belonging to this S r °^ , 
present a very remarkable uniformity of shape, at the same time 
the colours are very fine, and much varied in design. The she 
