10 Mr. C. Cliilton on a new Species of 



The appendages of the pleon are of small size in accordance 

 with the size of the pleon itself, and tliej are rather difficult 

 to dissect out satisfactorily ; but, so far as I have made tiiem 

 out, they present a fairly close general resemblance to those 

 of lanthe speciosa as described by Bovallius. 



In the viale the Jirst pair of appendages (Plate If. figs, lib 

 and lie) arc 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 tlie 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 sette. On the 

 underside the surface of the ])lates is quite flat and the lateral 

 margins are entire (fig. III). On the upper surface near 

 the middle there is on each side a thin ))late ))rojecting 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 (Hg. 11 c). The whole apparatus ))robably 

 serves to pass on the si)ermatozoa from the genital openings 

 in the seventh segment of tiie 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 II. fig. 12) have the main 

 portion subtriangular, the inner edge nearly straight, outer 

 edge curved and bearing a few short setaj towards the sub- 

 acute extremity. This portion, which both Bovallius and 

 Eeddard consider the '' protoi)odite," 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 o})posite direction, slightly curved, and 

 ending in a long, very acute extremity, a{)parently 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 t/iird pkopoda (PI. II. fig. 13) consist of a basal jior- 



