342 PhokidjE. MOLLUSCA. Atlantid^e. 
elongated aperture, with a long recurved canal in front, 
“ The adventitious pieces of shell are so disposed as 
and ending posterioilj' in a canal ascending the spire. 
not to curve downwards beyond the edge of the shell, 
The outer lip is thickened, expanded, and produced 
so as to impede the progress of the animal, but are 
into tubular spines or claws, in the young shells 
usually placed with their concave sides uppermost.” — 
appearing in tlie form of open canals, but in the adult 
Adams. 
becoming closed and solid. The species are only about 
In the two preceding families the foot of the animal 
ten in number, and all come from the Indian and 
was compressed, narrow., and adapted for leaping. In 
Chinese seas. 
the two succeeding ones this organ is compressed, 
erect, and fin-like. It is generally furnished with a 
small flat disk, or sucker, on the hinder edge. The 
I'amily — PHOK lUil!! {The (Jarrier Shells). 
body of the animal is more or less spiral in form, and 
the creatures appear adapted for floating on the surface 
The species of this family have a trochiform shell. 
of the water. The head is distinct, with an elongate 
with the aperture simple in front. The operculum is 
proboscis. The gills are not regularly comb-like, but 
large, horny, somewhat annular, triangular in shape. 
are tufted.* 
with the nucleus external. We are indebted to Mr. 
A. Adams for a very interesting account of the animals 
Family— PTEROTEACHEID^.. 
of these curious shells, whose history at present is so 
little known. “ The Phori," he says, “ are very 
Genus Carinaria. — This is the only genus in the 
numerous in the China and Java seas, living in from 
family that is provided with a true shell. The species 
fifteen to thirty fathoms water, and generally preferring 
are well known by the name of Glassy Sailors. The 
a bottom composed of the detritus of dead shells and 
shells are hyaline, symmetrical, conical, compressed. 
sand mixed with mud. As a curious adaptation of 
with a recurved apex, and a fimbriated dorsal keel, like 
means to answer a certain purpose, the mode of pro- 
the keel of a boat. It is exceedingly small for the size 
gression of these singular Molluscs is peculiar, and 
of the animal, which is large and translucent, and 
deserving of notice. The}' crawl like a tortoise, by 
indeed only covers and protects the nucleus, which is 
lifting and throwing forward the shell, with the tentacles 
peduncled, and in which are contained the more deli- 
stretched out, the proboscis bent down, and the oper- 
cate organs essential to life. They are found in the 
culum trailing behind. As they invariably inhabit 
Mediterranean, and in the Atlantic and Pacific oceans. 
places where the surface is rough and would not admit 
They are swift in their movements, and dart with great 
of a gliding motion, Nature has ordained that they 
rapidity through the water in a reversed position and 
should progress by a succession of small jumps or 
by a continuous effort, their body straightened, and 
tumbling evolutions. They are small for the size of 
their caudal fin undulating from side to side, and acting 
the shell, and have much the general appearance of the 
as a powerful natatory organ. They appear to prefer 
animal of Stromhm, like which they appear to walk ; 
the twilight, when they may be taken by the trawl in 
hut their eyes are sessile. In order to enable them to 
considerable numbers. They are supposed to feed 
escape from their enemies. Nature has instructed them 
to cover their shells with the same materials as those 
upon Acalephce and small Pteropods. 
of the banks which they inhabit. Sometimes for this 
purpose they select sand, often small stones, and more 
Family— ATLANTIDA l. 
frequently the debris of dead shells belonging to other 
Genus Atlanta. — T his is the only genus that has 
genera.” They are called, in consequence, Mineralo- 
a calcareous shell ; it is spiral, compressed, glassy. 
gists and Conchologists by collectors. 
transpaient, and underneath conspicuously keeled. 
Genus Phorus. — Phorus has the trochiform shell 
The Atlants are beautiful and sprightly little creatures. 
concave beneath, with thewhirls flat, the spire depressed. 
twisting their bodies about, and swimming in every 
the aperture wide, and the umbilicus small. The 
direction, at the same time probing every object 
species appear each to have its own peculiar method 
within their reach by means of their long muzzle- 
of collecting the fragments of shells and stones which 
shaped heads. 
cover the ground where it lives, and each cements to 
The genus Oxygyrus is distinguished by having a 
the outside of the shell its particular kind of materials. 
cartilaginous shell. 
Order II.— SCUTIBEANCHIATA. 
This order of Molluscs is much less numerous in species 
than the preceding. They are, with few exceptions. 
Family I.— PROSERPINIDAl. 
as Proserpina and Neritina, marine, and chiefly littoral 
In this family the shells have the aperture lunate. 
in their habits, living upon the sea-weed covering the 
the lips simple and sharp, and the throat furnished 
rocks along the shore. The animals are hermaphrodite 
and self-impregnating, the sexes not being separate as 
* The species belonging to this group have by many authors 
been arranged in a distinct sub-class by themselves, under the 
in the Pectinibranchs. 
name of Heteropoda or Cyclobrancliiata. 
