Order 1. Div. II. 



BRAJ^CHIOPODA. 



437 



Kg. IG.— Zoea. 



Zoea, Bosc, having the eyes larg;e, p;lobuIar, and entirely uncovered, with the tliorax cornuted. Z. Pelagica, 



Bosc, found in the Atlantic Ocean ; Monocidus Taurus of Slabber ; and probably 

 the Cancer Germamis of Linnaeus. [These curious creatures, of which Latreille 

 observed that they had not been sufficiently studied, and at the same time re- 

 gretted that he had never been able to obtain a specimen, have recently attracted 

 a great deal of attention, from having been asserted to be merely the larvae of 

 Decapod Brachyurous Crustacea, such as the common edible Crab, &c., by Dr. 

 J. V. Thompson, who, in his Zoological Researches, and other memoirs published 

 in the different scientific periodicals, has given figures of many new species, with- 

 TIl \^iy 1^^ *"^'' however, gaining a knowledge of the perfect analogy which exists between 



^— !s 3»w5W/r*s_ the organs of these animals and the Macroura. Having fortunately been enabled 



to dissect a very large species of this singular group, I have ascertained that 

 the supposed legs are merely the two outer pairs of foot-jaws immensely de- 

 veloped; the five pairs of true thoracic legs existing beneath the carapax. (See 

 my memoir, published in the Philosophical Transactions.) M. Milne Edwards 

 treats of them as Crustacc's douteux, and thinks it possible that they may be the 

 young of some of his Anoniourous order. In this state of the question (the change 

 from a Zoea to a Crab never having been observed, although the genera Mega- 

 lopiis and Macropa of Latreille are affirmed to be the intermediate stage), all that 

 can with certainty be arrived at is, that Zoea is a Malacostracous animal, be- 

 longing to the order Decapoda, and that it must consequently be removed from 

 the Entomostraca.] 



Nebalia, Leach, has the eyes flattened, and in part covered by a triangular channelled scale. Tlie legs are 

 fu)x;ate ; and the appendages at the extremity of the body setaceous. K. Herbstii, Leach and Desmarest ; and 

 N. Geoffroyi, Edwards. The latter is described, in a very detailed mannei-, by M. Milne Edwards, in the Annales 

 d€s Sciences Naturelles, [vol. xiii. pi. 15]. The rostrum in front of the shell is articulated at its base. The eyes 

 are peduncled : the superior antennae are inserted beneath them, with the second joint furnished with an oval 

 ciliated plate. [The terminal part is 9-annulated : these organs are elbowed, and bent down in front. The in- 

 ferior antennae are longer, more slender, and equally directed downwards : they consist of four strong basal joints, 

 and nine long terminal annuli. The shell is oval, and the animal considerably resembles a small short Shrimp, 

 only the legs are very short, bifid, and inserted far behind. Between them and the mouth, there are, however, 

 five pairs of minute, lamellose appendages, which probably represent the hinder foot-jaws and the fore-legs. The 

 abdomen is long, slender, nine-jointed, and terminated by two bifid appendages.] 



The Nebalie vent rue of Risso (Journ. Phi/s., Oct. 1822) probably constitutes a distinct genus in the section of the 

 Schizopoda. In the Cyclops exiliens of Viviani, the thorax is divided into several segments, which excludes it 

 from Nebalia. It also forms a subgenus intermediate between the preceding and following. 



Cuma, Edwards, is allied to Condylura, but the superior antennae are rudimental, and consist of a single joint. 

 The head is distinct from the thorax, which is divided into fom- segments, of which the first supports the four 

 fore-legs, and each of the three following another pair. All the legs are natatory, directed forwards, and without 

 hooks at the tip. The two first pairs are alone bifid. [.M. Edwards placed it amongst the Araphipoda. The 

 Cancer scorpioides of Montague, overlooked by all Crustaceologists, appears to be congenerous. Type, Cuma 

 Audouinii, Edwards.] 



Condylura, Latr. The inferior antennae are longer. The anterior sides of the first segment are prolonged and 

 pointed, forming two scales close together like a beak. Some of the middle feet are furnished, like the Schizo- 

 pods, with an outer appendage close to the base. The tail is narrow, 7-jointed, the last being long, conical, 

 and extends between the two slender, styliform, 2-jointed lateral aijpendages. C. Dorbignii, Latr. From the 

 coast of La Rochelle.* 



The other LopTajropa of the first clmsion, and in wliidi the thorax is divided into several segments, 

 the first being by far the largest, are only furnished with a single eye, situated in the middle of the 

 forehead between the upper antennse, constituting the genus 



Cyclops, Miill., studied by the elder Jurine and Ramdohr. The body is more or less oval, soft, or gelatinous, 

 divided into two portions ; the one anterior, composed of the head and thorax, and the other posterior, or the tail. 

 The first segment of the latter, in the female, bears two minute feet, and is not always easily distinguishable 

 from the thorax. The tail is 6-jointed : the terminal joint forked, and more or less furnished with feather-like 

 filaments. The anterior part of the body is divided into four segments. The first, being the largest, composes 

 the head and part of the thorax : it bears the eye, four antennae, two palpigerous mandibles, two niaxillie, and four 

 legs, each divided into two cylindrical stems. Each of the three following segments is furnished with a pair of 

 feet. The two upper antennae are long and multiarticulate, assisting in locomotion, having nearly the action of 

 feet. The inferior antennae are much sliorter, filiform, and generally four-jointed. By their rapid movements, 



• Nicothoe, Aud. and Kdw., would belong to this section if fur- 

 nished witii mandibles and maxillEe ; but as it is a parasite, and as I 

 tniuk I have observed in it the vestif^es of a sucker, I have placed it 

 tn the order Poecilopoda. Its legs, and the mode in which it carries its 

 epgs, agrees with Cydops. Pontia, Edwards, appears to be allied to 

 Cyclops. The head is distinct from the trunk, and terminated by a 



rustruiu, which is rather acute, and apparently two-jointed. It has ' procably allied to the aboic] 



two sessile eyes ; four ^utenniB, the superior [long], setaceous, and 

 multiarticulate, the inferior leg-like, and twu-branched. The thorax 

 is composed of five segments, and supports five pairs of bifid swim- 

 ming legs. The abdomen is two-juinted, and terminated by two 

 spatulated appendages. [Type, P. Sai'igniiy Edwaxds. The ^no 

 pkerura minuiisiiina, Templetou I^Trans, Knt. Soc, vol. L pi. 20), il 



