94 



HABITAT. The animals live in the branchial cavity of Cumacea, causing a gradual 

 swelling of the carapace above the place which is occupied by the parasite and its ovisacs. 

 A parasite with several ovisacs may be found on immature specimens of both sexes as well 

 as on adult females. Two infested adult males have also been found. The larvae infest not 

 only immature specimens, but frequently also females with marsupium. The two species 

 here described come respectively from Denmark and from Messina (and a deep-sea species 

 was found on a JDiastylis brought home by the »Ingolf« expedition) 1 ). 



.REMARKS. The genus is distinguished partly by the shape of the trunk-legs, 

 partly by the similarity of both pairs in the male as well as in the two sexes mutually, and 

 by their resemblance to the caudal stylets. In giving the genus its name, I have tried to 

 allude to this conformity in the appendages. The females are very small, more so than in 

 any other genus, which harmonises well with the scanty room left for them in the branchial 

 cavity of their rather small hosts. The males, on the contrary, are uncommonly large in 

 proportion to the females: in the large species about half the length, in the small one even 

 longer than a middle sized adult female. (In R. mediterranea the antennulae of the male 

 are decidedly 2-jointed; what in fig. If on pi. XIII appears to be a short basal joint, is an 

 angular excrescence proceeding from the head. On the other hand, the antennulae of R. 

 minuta sometimes appear to be 3-jointed, as the two last joints, though coalescent, are 

 separated by a distinct line, which, however, is too strongly marked in the drawing.) 



Conspectus of the Species. 



In the female the basal joint of the maxillipeds is comparatively more slender, a 

 good deal longer than half the breadth of the head at its base. Trunk-legs and caudal 

 stylets of the male are long, longer than half the breadth of the body, and furnished with 

 hairs about all over the distal half 1. R. minuta n. sp. 



In the female the basal joint of the maxillipeds comparatively stout, scarcely longer 

 than half of the head at its base. Trunk-legs and caudal stylets of the male shorter, not 

 nearly half the breadth of the body, and with very few or no hairs . 2. R. mediterranea n. sp. 



I. Homoeoscelis minuta n. sp. 



(PI. I, fig. 3a— 3b; pi. II, fig. la— 11). 



FEMALE. The largest specimen (fig. 1 b) , which had not begun laying eggs , is 

 ■52 mm. in length and - 49 mm. in breadth. A female which has nearly finished laying eggs 

 (fig. 1 c) is only -35 mm. long and 39 mm. broad. The frontal margin has seven small incisions 



*) J. Bonnier, in his above-mentioned treatise, published probably in Febr. 1S97, under the name of 

 Sphceronella sedentaria Bonn, described a species belonging to this genus. He found it in the branchial 

 cavity of Cyclaspis longicaudata G. 0. Sars, taken in a depth of 960 metres in "Le Golfe de Gascogne". 



