two sides, of the thickness of the back ; the sac, having no fins, re- 

 sembles an oval purse ; eight feet, all of Avhich are about equal, very 

 large in proportion to the body, and united at the base by a mem- 

 brane ; they i.re employed by the animal in swimming, crawling, 

 and seizing its prey. The length and strength of these limbs render 

 them fearful weapons, which it twines round animals ; in this way it 

 has even destroyed men while bathing. The eyes are small in pro- 

 portion, and the skin contracts over them so tightly as to cover them 



Genus Belemnites.. 

 .... Oithocera . . 

 .... Nodosaria . . 

 .... Hippurites . . 

 .... Conilites . . 



'First Family.— Les Orthoc<5r^es 



hollows of rocks. They are all carnivorous, living on crabs or any other marine 

 animals which they are able to catch, the singular position of their arms greatly 

 facilitating the necessity they are under of bringing their prey to their mouths, 

 ■where the two strong mandibles enable them to break and crush the hard bodies 

 ■with ■which some of their food is covered. Some of them are entirely naked ; 

 others live in a thin unilocular shell, which envelopes them, and in which they float 

 on the surface of the water ; and there are others which have a multilocular shell, 

 either completely or partially internal. 



First Division — Cephalopodes-jiolythaiames.Clmmerges) 

 Testaceous C^phalopodes — Shell multilocular, enveloped completely, or only parti- 

 ally enclosed in the posterior part of the animal's body, often closely adhering. 



r Shell multilocular, with 

 septa plain and sim- 

 ple at the edges, the 

 divisions of them not 

 exhibiting any su- 

 tures on the internal 

 thickness of the sub- 

 stance: shell straight 

 or nearly so ; not in 

 a spiral form. The 

 greater number of 

 these shells are only 

 known in a fossil 

 state. 

 Shell party in a spiral 

 form, the whorls se- 

 parated or connected 

 with each other, the 

 last continued in a 

 right line. The sep- 

 ta are generally tra- 

 versed by a syphon, 

 which in some spe- 

 cies being continued 

 in a straight line, 

 occasions the last 

 one to have from 

 three to six perfora- 

 tions. The first ge- 

 nus is known in a 

 recent state only ; 

 and P^ron has as- 

 certained that the 

 body of the animal 

 is contained in the 

 last septum only, and 

 the shell enveloped 

 by its posterior part. 



Spirula 



Spirolina 



Lituola 



ina .... > 

 a J 



Second Family. — Les Lituol^es < 



