39 
times with processes, whereas in the female there are no processes and fewer or no hairs 
etc. In Mysidion commune the male possesses on the outer side of the basal joint a knot- 
like excrescence and a process of very considerable size (pl. XI, fig. 3g and fig. 3h), and 
its second joint has a conspicuous process, all of which are wanting in the female. In Aspi- 
doecia (pl. XII) the female lacks maxillipeds; in the male, though somewhat smaller than 
usual, they are well developed: the basal joint is much as in Stenothocheres, but the second 
joint, which as in several other forms consists of two completely fused joints, is exceedingly 
short, somewhat shorter than the terminal joint. 
Trunk-legs and caudal stylets. The occurrence of these organs is mentioned above 
on p. 36. In Homoeoscelis (pl. IL and pl. XIII) there is but a slight difference between 
the two similarly shaped pairs of trunk-legs and the caudal stylets, and as both are like 
those of the female, they do not require further mention; we shall only add that they are 
sometimes rather larger than, sometimes of the same size as those in the other sex. In Sfenotho- 
cheres (pl. I) the trunk-legs are very similar to those of the female and of almost equal size, 
however, as the trunk of the female is large, that of the male small, of course the legs of the 
latter are much more conspicuous and appear larger. In the male the basal part of the legs 
stands more out from the body, and the longer robust terminal spine on the outer branch is 
longer than in the female; the other differences are insignificant. Thus, in Stenothocheres 
Sarsii the spine on the inner branch of the second pair of legs is curved like a hook, in 
Sten. egregius it is less curved, and in the illustrated specimen the right and the left spine 
curve differently. Behind and above the basis of the second pair of legs both species show 
two considerable spines which are situated close together on a small projection; L should 
think they might possibly be considered as rudiments of a third pair of legs, but I do not 
presume to have any definite opinion about the matter. The abdomen is small, with short, 
distinct, rather broad stylets, not set off by an articulation, and each provided with four 
spines, of which the two innermost are the longest and thickest. 
In Spheronella, as a rule, there is a great difference between the two pairs of trunk- 
legs and between each of these and the caudal stylets. The shape and size of the trunk- 
legs vary much according to the species, and the appearance of the legs as well as of the 
stylets presents very great variation on account of the very different length of their terminal 
sete. In this genus the first pair of legs usually originates outside and behind the basis of 
the maxillipeds, nearly in the middle between the lateral margins and the median line of the 
trunk, at the bottom of a pretty broad transverse depression. Each leg consists of a basal 
part, a peduncle, differing much in length and breadth (sometimes, as in Spher. intermedia 
(pl. V, fig. 3f and fig. 3g), this part in exceedingly large), and of two branches, one of 
which is generally longer than the other, sometimes the one is wanting altogether. As a rule, 
none of the branches are articulated on the peduncle, and frequently one or both of them 
terminate in sete, one of which is longer than the others, the one on the outer branch 
often exceedingly lony, occasionally half as long as the whole animal. The second pair of 
