families, viz., ('/ni/xlo', Vaunthompsoniidce, /;<n>i.i>r<ij>i<l<t', Leucui/i<ln', /)i<txli//i.<lce, 

 Pseudociimiflw, Cumellidce and Campylaspidce. This classification, the only one as 

 yet proposed, is followed in the present account, except that one new family, 

 Pl(tl//<txjii<l<t', has been established, to include the anomalous genus Flaiyaspis, 

 formerly referred to the Lampropidce. 



General characters of the Cumacea. 



The external appearance of the Cumacea is quite particular and unlike that 

 of any other Crustacea. The slenderness and extreme flexibility of the posterior 

 division or tail is especially very characteristic, and has given rise to the first 

 specific names given, viz., scorpioides (with a tail like a scorpion). The anterior 

 division is much broader, in some cases exceedingly tumid, and sharply marked 

 off from the slender tail, whereas in other cases it gradually tapers behind. 

 In all the known forms, this division is covered anteriorly by a well-defined car- 

 apace, behind which, never more than 5 segments of the mesosome are exposed. 

 By this character, the Cumacea undoubtedly approach nearer to the Podophthal- 

 mia than to the Edriophthalmia, among which, only the cheliferous Isopoda ex- 

 hibit any sign of the formation of a carapace by the fusion of the cephalon 

 with the 1st pedigerous segment. The structure of the carapace is very peculiar, 

 especially as regards its anterior part. In the greater number of forms, it pro- 

 jects in front to a more or less distinct rostriform prominence, covering the 

 bases of the antenna 1 . On a closer inspection, however, this rostrum-like promi- 

 nence is found to be very different from the so-called rostrum in other Crustacea. 

 In all cases, it is found to be composed of 2 juxtaposed lappets, which are generally 

 closely applied to each other along the dorsal line, without, however, in any 

 case coalescing, a narrow fissure being always present between them. This 

 fissure at the base of the prominence, divides into 2 diverging rami, encompas- 

 sing a bell-shaped dorsal area of the carapace, the frontal lobe. Of course the 

 lappets forming the pseudorostral prominence, originate at the points where the 

 lateral fissures terminate, and more properly represent the antero-lateral corners 

 of the carapace, which are developed in a very peculiar manner, to encompass 

 its frontal part. Below them, the anterior edges of the carapace often project in 

 the form of a triangular lobe ; and from the sinus between these lobes and the 

 pseudorostral prominence, the antennae are seen to project. The lateral parts of 

 the carapace form a narrow duplicators below, turning abruptly inwards and limit- 

 ing the oral area, which is rather narrow. They do not loosely cover the sides 

 of the body, as in the greater number of the Podophthalmia, but are firmly con- 

 nected with it along their edges, only leaving 3, small slit on each side of the 



