Si cE ame ge a Rl ge pic: lp 
of the Fishery Board for Scotland. 213 
with three slender processes; two of them are prolongations of the 
lateral angles, and the other of the intermediate angle by which the 
posterior edge of the plate is divided into two sub-equal portions. It has 
to be noted, however, that these dorsal expansions are so extremely 
delicate that, though many specimens have been examined, it was rare to 
find one with the appendages uninjured. The following is M. Hesse’s 
description of the posterior dorsal plate :—‘‘Enfin la sixieme expansion 
membraneuse que est aussi triangulaire comme celle placée sur ]’occiput, - 
est fixée un peu audessus de la base de l’abdomen qu il recouvre, et 
semble destiné 4 protéger les oeufs ou les embryons. Son bord inférieur 
présente deux découpares, terminées per trois laniéres, dont |’une est au 
milieu et les deux autres & l’extrémite du bord inférieur.” 
The cephalo-thorax in the female is comparatively large, and consists of 
five segments ; in adult specimens, however, the segments are not very 
clearly defined. The first four do not differ much in size, but that 
which forms the head or cephalosome is rather smaller than the others. 
The last segment is fully twice the length of the preceding one, and is 
composed of two coalescent segments—the fourth and fifth segments of 
the metasome. This double segmeut is destined, as in other members of 
the NVotodelphyoida, to be a receptacle for the eggs and developing larve, 
and when packed with eggs or larve it becomes considerably enlarged, 
and is also more highly coloured than other parts of the animal. (See 
fig. 1. 
In se female the abdomen—wrosome—-is moderately elongated, 
slender, and cylindrical, and is composed of five segments, but the 
prefurcal segment is very small and of a peculiar structure, and seems to 
overlap the base of the short furcal joints. These joints, which are 
somewhat arcuate, are each armed with about four very short but strong 
curved spines (fig. 19). 
Neither the male nor the young female appears to be furnished with 
the prominent dorsal appendages possessed by the female that has 
reached the ovigerous stage. Figure 3 represents a young female with an 
adult male adhering to its dorsal surface, in both of which the wing- 
like expansions are wanting. The female appears to have reached the 
stage when these expansions vre beginning to be developed, but in the 
male no trace of them can be observed, though its structure shows it to 
be a mature example. 
In the specimens under consideration the antennules (anterior 
antenne) are in both sexes apparently nine-jointed. In those of the 
female the first two joints are of large size, but the remaining joints are 
considerably shorter and narrower, and the second and third from the end 
are smaller than any of the others. The male antennules are moderately 
stout and taper gradually towards the distal extremity ; the first two 
joints are not so dilated as the first two in the female, but the remaining 
seven joints are rather larger. (See figs. 4 and 5.) 
The antennz (posterior antenne) of the male, though considerably 
smaller than those of the female, are similarly armed with strong 
terminal claws, as shown in figs. 6 and 7. 
The mandibles are well developed and possess a broad, biting edge, 
armed with several irregular teeth; the mandible-palp is moderately 
large and two-branched ; the proximal branch appears te be uni-articulate, 
but the other is two-jointed ; both branches bear plumose sete (fig. 8). 
The maxille (fig. 9) are also moderately developed and supplied with 
numerous plumose setz. 
The first maxillipeds have the basal part greatly enlarged and 
provided with a number of long plumose setz on its inner margin; the 
