42 
joints narrow and elongated, forming angular bends with each other; 2nd pair 
likewise slender, though shorter, and exhibiting the full number of joints. Both 
these pairs in female with well-developed natatory exopodites, the 3 posterior pairs 
simple. All the legs in male, except the last pair, provided with very fully de¬ 
veloped exopodites. Pleopoda in male only 2 pairs. Uropoda slender, with the 
hasal part very narrow and spinulose inside, inner ramus triarticulate, outer In¬ 
articulate. Telson well defined, with the outer part generally narrowly produced 
and spinulous, tip with only two spinules. Sexual dimorphism generally very 
pronounced. 
Remarks .—This family is well distinguished from the other Cumacean 
families by a number of easily recognizable characters. As to the external ap¬ 
pearance, the sharp demarcation between the anterior and posterior divisions of 
the body is rather characteristic, the former being generally very tumid, whereas 
the latter is always extremely narrow, with the segments connected in a parti¬ 
cular manner, so as to admit of very great mobility, not only in a ventral, but 
also in a dorsal direction. In all the known forms, the anterior extremity of the 
body is produced in a nose-slmped prominence, the pseudorostral projection, and 
the posterior in a more or less elongated, narrowly lageniform piece, the telson, 
which projects between the slender, diverging uropoda. The structure of the an- 
tenme is rather unlike that in other Cumacea, and in the structure of the other 
appendages also, several peculiarities are to be found. As to the number of 
pleopoda in the male, this family agrees with the Leuconidce, but is otherwise 
very different. The family comprises as yet 5 genera, 4 of which are represented 
in the Norwegian fauna and will be treated of below, the 5th, Pachystylis, having 
recently been established by Dr. Hansen, to include an exotic form from the 
German Plankton-Expedition. 
Gen. 1 . Diastylis, -Say, 1818. 
Syn: Condylura , Latreille (not Illiger). 
„ Alauna y Goodsir. 
„ Cuma , Kroyer (not Edwards). 
Generic Characters .—Body in female rather robust, in male much more 
slender. Integuments generally hard and brittle, exhibiting an irregular reticulated 
structure, and more or less densely hairy. Carapace large and tumid, not infre¬ 
quently armed with spiniform projections, sometimes also with lateral folds, but never 
