of legs. In the structure of the oral parts also, several well-marked differences are 

 to be found. Thus the mandibles are provided with distinct palps, always wanting 

 in the Tanaidce, and the maxillae are more fully developed, the anterior ones 

 having 2 masticatory lobes, and the posterior ones exhibiting all the parts cha- 

 racteristic of the typical Isopoda. Finally, the epignath of the rnaxillipeds is of 

 an essentially different shape, and much more fully developed than in the Tanaidce. 

 The family contains as yet 5 genera, viz., Apseudes Leach, Sphyrapus Norm. & 

 Stebb., Parapseudes G. 0. Sars, Typhlapseudes Beddard, and Leiopus Beddard. 

 Of these the 2 first-named genera are represented in the fauna of Norway. 



Gen. 1. ApSeudeS, Leach, 1814. 



Syn: Euplieus, Kisso. 

 Rhoea, M. Edw. 



Generic Characters. - - Body, as a rule, very slender and attenuated, with the 

 segments generally sharply marked off from each other. Cephalosome rather broad, 

 depressed, more or less distinctly sculptured above, and generally terminating in front 

 in a flattened rostral plate. First free segment of mesosome rather firmly connected 

 to the cephalosome, and having the coxal plates spiniform, pointing obliquely 

 in front. Metasome very narrow, more or less hairy, with the terminal segment 

 rather produced. Ocular lobes generally well-defined, with or without distinct 

 eyes. Superior antennae of similar structure in the two sexes, both flagella rather 

 elongated. Inferior antennae furnished at the end of the peduncle outside with 

 a scale-like setous appendage. Mandibles rather strong, cutting part divided into 

 2 superposed dentated lamellae and having behind a dense bunch of slender spines 

 doubly or trebly forked at the tip, palp well developed and densely setous. Chelipeds 

 in male larger than in female, with the hand more tumid and the thumb tuber- 

 culated inside. Fossorial legs rather strongly built and of similar structure in the 

 two sexes. All the pleopoda distinctly developed, rami uniarticulate and clothed 

 with long ciliated setae. Uropoda with the ranii very slender, filiform, being 

 composed of numerous short articulations. 



Remarks. This is the first recorded genus, and may therefore be regarded 

 as the type of the family. It is chiefly characterised from>the next genus by 

 the slender body, the flattened and distinctly sculptured cephalosome, the presence 

 of a well-defined scale-like appendage to the inferior antennae, and the less pro- 

 nounced sexual differences, as regards the superior antenna? and the first 2 pairs 

 of legs. The genus contains several species from different parts of the Oceans, 



