'•i50 



ARTICUJ.ATED ANIM.ILS. 



il-l.irre fcr- 



In J,vn/,7/«,v, liron-., tlje ornlir tulicrcles apprar to (•-Jiiljit a cnvpiin^', or are aranular ; tlj<; 

 miiiatnig- the body, is less tlon-atcd tlian in Calyiiieiie, ami nearly seioieiixular, or iii the shap.;'of a slinrt I ri;n.;'-le,* 

 A 'n '-'.'//A'/'". -Uruii-., the slueM is loii^-er than hioad, «ilb the 



posterior ari;;les i.roduced into a spine. The ocular promi- 

 nences exhibit neither covering nor i;raiiiilatioiis. TIic body 

 ii elliplic. 



'i'lic^eeniincnees, having the appearance of eyes, either do 

 not exist, or are not <listinctly to be seen, in the genus Parn- 

 lioxiiles, Brong. Tlie segments, or at least tlie majority ol 

 tliem, extend laterally beyond the body, and are disengaged 

 at Hieir extremity on the sides. 



Such are the characters of tlie live genera established by 

 JM. Alex. Urongiiiart, and which may be arranged into three 

 groups : 1, the Reniforiiles (genus Ayiiostifi) ; '1, Ihei.'ontrac- 

 tiles (g. Calipiiene) ; 3, the Extensi (g. jUaphus, Oti'jii'ni, and 

 Paradoxides). "We refer for a knowledge of the species and 

 their respective strata, to the work of the above-mentioned 

 celebrated naturalist, who lias associated with him, in respect to the fossil Crustacea, M. Desmarest, so often cited 

 by ns in our accounts of fossil and recent (_'rustacea. (.)ther savans have proposed other genera amongst the Trilo- 

 Intes ; but being conlined to the most general con.^iderations, I can only cite those \^Ilich appear in the best 

 work yet published on these singular fossils. 



A.saplius 



■ollcil up. 



THE SECOND CLASS OF AllTICULATED ANIMALS FURNISHED WITH 



ARTICULATED LEGS,— 



ARACllNIDA,— 



Is, like the Crustacea, [composed of species] destitute of wings, and which are in a 

 manner not liable to change their form, not undergoing metamorphosis, but simple 

 shcddings of tlie outer covering of tlie body. Their sexual organs are pLiced at a 

 distance from tlie posterior extremity of the body, being (except in some males) at 

 the base of the venter. But they differ from these animals as well as from the true 

 insects in inany respects. As in the latter, the surttiec of tlieir bodies exhibits orifices 

 or transverse slits, named stigmata (but which it would be better to name Pnenmo- 

 stomes, — mouth for the air, — or spiracles, that is, respiratory orifices), serving for the 

 entry of the air, but being few in number, (eight at most, generally only two), and 

 situated only on the under side of the abdomen. Respiration is effected either by 

 means of aerial braiichiLc, ser\ing as lungs and inclosetl in bags, to wliieli these 

 spiracles form the entry, or by metins of radititiug tracheae. The organs of sight con- 

 sist only of minute simple ocelli, grouped in diif'erent positions wdien there is a 

 number of them. The head, generally united to tlie thorax, merely exhibits at 

 the place of the antenuEC two articulated pieces, like small didaetyle or monodactyle 

 claws, wdiicli have been iujutliciou^ly eomptired to the mandibles of insects, and so 

 named ; but they move in ;i direction opiiosed to tlie niotiuu of mandibles, or up 

 and down, its^isting, nevertheless, in eating, and replaced, in those Arachiilda which 

 have the mouth formed into a siphon or sucker, by two pointed plates, used as 

 lancets. f A sort of lower hp {labium, Fab.), or rather tongue, {laiigiietti-}, fornitd 



* iLi As'iphm, lirotn,niiurt, deseribytl and fi)riiri;.l \,y I\l, K. Dch 

 Clinmps, thu [losEcrior angles of the sliiclil, uisteaJ uf Ijeiiif dir 

 biietiwarrts, as in tlie other species, are reetirved. 



t Chclicenc, or anteiinal claws, lur saeh tlicy arc cvi.lcnti 

 proveil by a ui-mparisnn of these origans with ihe internicoiat 



ni ante 

 by prcei 



tiose of tlie i>rdcr Pa-'ilnondri, 

 a the .Irricliiiiiiu arc dc^htute 

 «tiich thcyha\c been defined 



