118 



Fam. 4. Desmosomidae. 



Characters. — Body more or less elongated, with the segments, as a rule, 

 sharply marked off from each other, the 3 posterior segments of mesosome gener- 

 ally defined from the 4 anterior by a well-marked constriction. Cephalon emar- 

 ginated on each side for the insertion of the antennae, frontal part more or less 

 produced. Caudal segment generally ' rounded at the tip. Eyes wholly absent. 

 Superior antennae, as a rule, small, and placed wide apart. Inferior antennas not 

 particularly elongated, sometimes different in the 2 sexes. Mandibles with or 

 without palps. Maxillipeds always lamellar, with the joints of the palp more or 

 less expanded. 1st pair of legs generally unlike the others, prehensile or very 

 slender. The 3 posterior pairs of legs in some cases natatory, with the outer 

 joints flattened, but never, as in the Munnopsidce, edged with ciliated setae. Uro- 

 poda generally small, bi- or uni-ramous. 



Remarks. — The present family is somewhat intermediate in character 

 between the Ianiridce and Munnopsidce, some of the forms resembling the former, 

 others the latter family. I have, however, thought it advisable to keep it apart 

 from both of them. All the known forms are blind, and generally have the body 

 narrow and elongated, with the segments, as a rule, very sharply marked off from 

 each other, so as to exhibit a more or less moniliform shape. The family com- 

 prises as yet 6 genera, all of which are represented in the fauna of Norway. 



Gen. 1. NannoniSCUS, G. O. Sars, 1869. 



Generic Characters. — Body distinctly depressed, with the segments rather 

 densely crowded together, and lamellarly expanded laterally. Cephalon compara- 

 tively large, with the frontal part considerably produced. Caudal segment like- 

 wise larger than usual, semi-oval. Superior antennae extremely small, with the 

 peduncle apparently only consisting of 2 joints, flagcllum rudimentary, and carrying 

 outside a single, enormously developed olfactory papilla. Inferior antennae of 

 moderate size, with the peduncle 6-articulate, its 3rd joint being produced outside 

 to a strong, anteriorly pointing spine. Mandibles with the molar expansion rather 

 slight, conical, and tipped by a fascicle of slender bristles; palp distinct, 3-arti- 

 culate, though not very large. Maxillipeds pronouncedly lamellar, penultimate 

 joint of the palp produced at the end inside to a digitiform process; epignath 



