Order 2. Div. II. PCECILOPODA. 447 



fikiments at the extremity of the body as ovaries. I have sometimes found the e^g;s beneatli the posterior branchial 

 legs, but never in these tubes. In other cases, the external ovaries, thus elongated, are only found in those fenjales 

 which lay their egg's in holes or deep burrows; whereas this is not the case with the Caligi. Aliiller and other 

 zoologists have obser\'ed that these Cnistacea trim and agitate these appendages. We believe, together with both 

 the Jurines, that they sen'e for respiration, in the same manner as the anal filaments of Apus.* 



The species of the restricted subgenus CaUgits (including Risculus, Leach) have all the legs free, and attarhed> 

 with the exception of the two last, to the anterior part of the body (cephalothorax, Latr.), covered by the shield; 

 and some, at least, of the feet are furnished with nnmerous filaments. The siphon is not distinct. The abdomen 

 is naked above, and terminated by two long filaments or two styles. Caligus piscinus, Latr. ; C. curtus, Jliill. ; 

 Monocuhis piscinus, Linn. The Onhcus lutosus. Slabber, ought perhaps to form a distinct subgenus, on account 

 of the fin-like appendages. The Binocle a queue en plumct of Geoffroy may be introduced into this subgenus. 



[Messrs. Pickering and Dana have published an extremely elaborate description of a species of Caligus (C. ameri- 

 canus) found upon the Cod, as many as forty or more individuals occasionally occurring on a single fish; but they 

 are never found within the gill covers. The figures illustrating this memoir have never been surpassed.] 



[M. M. Edwards has published a memoir upon this genus in the Annalcs des Sciences Naturelles, especially with 

 reference to the structure of the mouth]. 



In all the other subgenera of Caligus, the upper side of the abdomen is imbricated, or this part of the body is as 

 though it were inclosed in a kind of case, formed by the terminal feet, which resemble membranes, and are turned 

 upwards. 



Pter>jgopoda,'ij&X,r. (Nogaus? Leach), has the posterior extremity of the body terminated by two fin-like ap- 

 pendages. It has digitated feet on the under-side of the post-abdomen, or second division of the body, not covered 

 by the shield, and a distinct beak. Founded upon a single species, found on the shark. ; 



Pandarus, Leach, has two filaments at the posterior extremity of the body. The legs, of the first and fifth pairs, 

 are ungTiiculated, and the others digitated. The siphon is not distinct. Pandarus bicotor. Leach ; P. Boscii, 

 Leach, &r. [Two other species of this genus have been described and figured by Dr. Johnston, in the Magazine 

 of Natural Histori), vol. viii.] 



Dinemoura, Latr., has two long filaments at the anus, but m which the siphon is distinct. The two fore-legs 

 are unguiculated ; the two following are tenninated by two long fingers ; the others are in the form of membranous 

 leaflets. C. productus, MuUer; M. salmoneus, Fabr. 



Anthosoma, Leach, approaches the preceding, as regards the existence of the siphon and the two anal filaments ; 

 but it recedes from it, as well as the two preceding, in its antennae, of which two are directed for\vards, in the 

 shape of small monodactyle claws, and in the six faind-legs, which are membranous, folded upwards, at the sides, 

 upon the post-abdomen, which they envelope. The first and third pairs of legs are imguiculated ; and the second 

 terminated by two short, obtuse fingers. Anthosoma Smithit, Leach. 



[Nemesis, Risso, is a curious genus, of a narrow form, with the anal filaments many tinies longer than the entire 

 body.— See Pol. Rouj:, Crust. Mediter., pi. 20.] 



In the second subtribe of the Caligides, the body is oval, without exserted anal appendages, in the 

 form of filaments or fin-like scales. A portion of the superior integuments composes in front of the 

 body a shield, which does not cover the anterior half, narrower than it, rounded, and notched anteriorly, 

 dUated and bUobed at the other end, succeeded by three other pieces, or rounded scales, posteriorly 

 notched, the second of which is the smallest, being in the shape of a reversed heart; the last is the largest. 

 The four posterior legs are in the form of plates, united in pairs ; those of the first and third pairs are 

 unguiculated ; the second are bifid at the tip. The siphon is apparent. The eggs are covered by two 

 large, oval, contiguous, coriaceous pieces, placed beneath the abdomen, and sui-passing it in length. 



Such are the characters of the genus 



Cecrops, Leach, of which a single species is only known, which has been found fixed to the branchiae of the 

 tunny and turbot. C. Latreillei, Leach. 



The second of the tribes of the Siphonosfoma — that of the LerNjEiformes, Lat., — is composed of 

 Entomostraca still nearer allied than the preceding to the Lemajae. The number of the legs does not 

 clearly exceed ten, (but there is perhaps another pair still more minute), and these organs are, for the 

 most part, -very short, and unfitted for swimming. Sometimes the body is nearly vermiform, cylindric, 

 with the anterior segment simply a httle wider, and furnished with two didactyle advanced claws, and 

 sometimes, in consequence of two lateral expansions in the shape of lobes or wings, directed behind 

 the thorax, and of tlie two ovaries, which are posterior, it forms a small quadrilobed mass. This tribe 

 comprises two genera. 



• In the thiri Tolnme of the Annat. Gencr. des Sci. Physiq., p. 343, 

 printed at Bnissels, there is an extract from the observations of Dr. 



closing a living foetus, very different from its parent, and of which hfc 

 gives a descriptiiin. From these obsen-ations, these filaments would 



Surriray, upon the foetus of a species of Caliyus (C. rlovg^tusP) which seem to be exterior oviducts •, but is there nut some error in this 



ts very common upon the operculum of £toj 5<-?onp. This naturalist statement? I have studied, with great care, these organs in many 



stites, that, having crushed the anal filaments of the animal, he ob- specimens— prcsen-ed, it is true, in spirits of wine— but 1 have never 



served many membranous and transparent eggs discharged, each iu- yet discovered any body inc)o.s-d in tlicm. 



