10 Mr. C. Chilton on a new Species of 
The appendages of the pleon are of small size in accordance 
with the size of the pleon itself, and they are rather difficult 
to dissect out satisfactorily ; but, so far as I have made them 
out, they present a fairly close general resemblance to those 
of lanthe speciosa as described by Bovallius. 
In the male the first pair of appendages (Plate II. figs. 11 5 
and 11c) are modified to form an accessory male organ. 
They consist of two more or less oblong plates fitting closely 
against one another along the median line; they are widest 
at the base, where the outer margins are strongly convex ; 
towards the middle they narrow considerably, widening again 
slightly towards the distal end; the extremity of each part is 
curved and bordered with about eight short sete. On the 
underside the surface of the plates is quite flat and the lateral 
margins are entire (fig. 116). On the upper surface near 
the middle thereis on each side a thin plate projecting upwards, 
so that a kind of groove is formed between them, the top of 
it being no doubt closed by the next pair of pleopoda fitting 
on to it above. ‘Towards the end the surface is raised on 
each side into two ridges which converge towards each other 
as they reach the outer distal angle, thus forming a duct on 
each side, which reaches from nearly the centre of the joint 
to the outer angles (fig. 11 ce). The whole apparatus probably 
serves to pass on the spermatozoa from the genital openings 
in the seventh segment of the pereion to the “ penial fila- 
ment’ of the second pair of pleopoda. On the under surface 
the two halves of the organ are separated along their whole 
length, but on the upper surface they are joined together from 
the base until the beginning of the ducts, only the distal 
portions therefore being completely separated. 
The second pleopoda (Plate Il. fig. 12) have the main 
portion subtriangular, the inner edge nearly straight, outer 
edge curved and bearing a few short sete towards the sub- 
acute extremity. ‘This portion, which both Bovallius and 
Beddard consider the ‘ protopodite,” contains a very powerful 
muscle, which reaches to the “ penial filament’ and no doubt 
acts as an extensor muscle for it. This filament appears to 
consist of two joints, one directed backwards towards the base 
of the appendage and the other when at rest lying alongside 
it, directed in the opposite direction, slightly curved, and 
ending in a long, very acute extremity, apparently grooved 
on the concave side. Beddard considers this ‘ penial fila- 
ment” to be the ‘‘ endopodite,” a small soft appendage which 
arises from near its base he considers as the ‘ exopodite.”’ 
The third pleopoda (PI. II. fig. 13) consist of a basal por- 
