129 



of the inner. Colour whitish, semi-pellucid. Length of adult female 4 mm., of 

 male 3 mm. 



Remarks. The present form was first described by the present author 

 as Desmosoma tenuimanum, and at the same time the anomalous characters of 

 this species were pointed out. The Eugerda globiceps of Meinert is unquestionably 

 the same species, and accordingly only the generic name proposed by that author 

 ought to be retained. In outward appearance, it bears a great resemblance to 

 Desmosoma lineare, but may, on a closer examination, be easily distinguished by 

 the more elongated inferior antennae, the extremely slender 1st pair of legs, and 

 the distinctly biramous uropoda. 



Occurrence. This species was first detected at Langesund, south coast of 

 Norway, and I have subsequently found it, though rather sparingly, in the inner 

 part of the Christiania Fjord, at Drobak, as also in the Trondhjem Fjord. 



Distribution. Skagerak and Kattegat (Meinert). 



Gen. 6. EchinOpleura, G. 0. Sars, n. 



Sj'n: Desmosoma, G. O. Savs (part). 



Generic Characters. Body slender, attenuated, and abruptly narrowed in 

 the middle, 4th and 5th segments of mesosome forming together, as in the genus 

 Ischnosoma, an hour-glass-shaped section. Caudal segment deeply constricted at 

 the base. Lateral parts of all the segments coarsely denticulated. Antennae of a 

 similar structure to that in the 2 preceding genera. Mandibles without palps, 

 cutting edge in the right mandible simple, in the left very slightly bifid, molar 

 expansion extremely small, dentiform, tipped by a single bristle. 1st pair of legs 

 but slightly differing from the 3 succeeding ones, all 4 pairs rather slender, and 

 edged with scattered spiniform bristles; the 3 posterior pairs still more slender, 

 imperfectly natatory, though approaching in structure those in the 2 preceding 

 genera. Uropoda simple, Inarticulate, distal joint the larger. 



Remarks. The present new genus is established, to include the rather 

 anomalous form previously described by the present author as Desmosoma acti- 

 leatum. On a closer anatomical examination of this form, I have found it to 

 differ in some points so materially from the 2 other species of Desmosoma, that 

 it should more properly be regarded as the type of a separate genus, in some 

 respects exhibiting some resemblance to the genus Ischnosoma. The structure of 



17 Crustacea. 



