a42 



Phorid.e.- 



-MOLLUSCA.- 



-Atlantid^. 



eIoiigat<'J aperlure, with a long recuived canal in front, 

 and ending postuiiorly in a canal ascending the spire. 

 The outer lip is thickened, expanded, and produced 

 into tubidar spines or claws, in the yonrjg shells 

 appearing in the form of open canals, but in the adult 

 becoming closed and solid. The species are only about 

 ten in number, and all come from the Indian and 

 Chinese seas. 



Family— PnORIDJi; {The Carrier Shells). 



The species of this fiimily have a trocliiform shell, 

 with the aperture simple in front. The operculum is 

 large, lioi'ny, somewhat annular, triangular in shape, 

 with the nucleus external. We are indebted to Mr. 

 A. Adams for a verj' interesting account of the animals 

 of these curious shells, whose history at present is so 

 little known. " The Phori," he says, " are very 

 numerous in the China and Java seas, living in from 

 fifteen to thirty fathoms water, and generally preferring 

 a bottom composed of the detritus of dead shells and 

 sand mixed with mud. As a curious adaptation of 

 means to answer a certain purpose, the mode of pro- 

 gression of these singular Molluscs is peculiar, and 

 ilcsorving of notice. They crawl like a tortoise, by 

 lifting and throwing forward the shell, with the tentacles 

 stretched out, the proboscis bent down, and the oper- 

 culum trailing behind. As they invariably inhabit 

 ]ilaces where the surface is rough and would not admit 

 of a gliding motion. Nature has ordained that they 

 should progress by a succession of small jumps or 

 timibling evolutions. They are small for the size of 

 the shell, and have much the general appearance of the 

 animal of Stromhiis, like which they appear to walk ; 

 but their ej"es are sessile. In order to enable them to 

 escape from their enemies, Nature has instructed them 

 to cover their sliells with the same materials as those 

 of the banks which they inhabit. Sometimes for this 

 purpose they select sand, often small stones, and more 

 frequently the debris of dead shells belonging to other 

 genera." They are called, in consequence, IMineralo- 

 gists and Conchologists by collectors. 



Genus Phorus. — Phoriis has the trochiform shell 

 concave beneath, with the whirls flat, the spire depressed, 

 the aperture wide, and the umbilicus small. The 

 species appear each to have its own peculiar method 

 of collecting the fragments of shells and stones which 

 cover the ground where it lives, and each cements to 

 the outside of the shell its particular kind of materials. 



" The adventitious pieces of shell are so disposed as 

 not to curve downwards beyond the edge of the sIkII, 

 so as to impede the progress of the animal, but are 

 usually placed with their coucave sides uppermost." — 

 Adams. 



In the two preceding families the foot of the animal 

 was comjiressed, narrow, and adapled for leaping. In 

 tlie two succeeding ones this organ is compressed, 

 erect, and fin-like. It is generally furnished with a 

 small fiat disk, or sucker, on the hinder edge. The 

 body of the animal is more or less spiral in form, and 

 the creatures appear adapted for floating on the surface 

 of the water. The head is distinct, with an elongate 

 proboscis. The gills are not regularly comb-like, but 

 are tufted.* 



Family— PTEROTRACHEIDiE. 



Gknus Caeinaria. — This is the only genus in the 

 family that is provided with a true shell. The species 

 are well known by the name of Glassy Sailors. The 

 shells are hyaline, symmetrical, conical, compressed, 

 with a recurved apex, and a fimbriated dorsal keel, like 

 the keel of a boat. It is exceedingly small fur the size 

 of the animal, wliich is large and translucent, and 

 indeed only covers and protects the nucleus, wliich is 

 peduncled, and in which are contained the more deli- 

 cate organs essential to life. They are found in the 

 Mediterranean, and in the Atlantic and Pacific oceans. 

 They are swift in their movements, and dart with great 

 rapidity through the water in a reversed position and 

 by a continuous effort, their body straightened, and 

 their caudal fin undulating from side to side, and acting 

 as a powerful natatory organ. They appear to prefer 

 the twilight, when they may be taken by the trawl in 

 considerable numbers. They are supposed to feed 

 upon Acahyhee and small Pteropods. 



Family— ATLANTIDiE. 



Genus Atlanta. — This is the only genus tliat has 

 a calcareous shell ; it is spiral, compressed, glassy, 

 transparent, and underneath conspicuously keeled. 

 The Atlants are beautiful and sprightly little creatures, 

 twisting their bodies about, and swimming in eveiy 

 direction, at the same time probing every object 

 within their reach by means of their long muzzle- 

 shaped heads. 



The genus Oxygvrus is distinguished by having a 

 cartilaginous shell. 



Order II.— SCUTIBRANCIIIATA. 



Tins Older of Molluscs is much less numerous in species 

 than the preceding. They are, with few exceptions, 

 as Proserpina and Ncritina, marine, and chiefly littoral 

 in their habits, living upon the sea-weed covering the 

 rocks along the shore. The animals are hermaphrodite 

 and self-impregnafing, the sexes not being separate as 

 in the Pectinibraiichs. 



Family T.— PROSERPINID^. 



In this family the shells have the aperture lunate, 

 the lips simple and sharp, and the throat furnished 



* Tlie species belonging to this group have Tiy many authors 

 been arrani^ed in a distinct sub-class by themselves, under the 

 name of IIetcroj)oda or Cyclobranchiata. 



