MONSTRILLA AND THE CYMBASOMATIDA. 119 
Of specimens of the various species of Monstrilla I have 
had no experience beyond some half-dozen which I have 
in all collected. Three of these, all females, are clearly 
M. rigida, 1. C. Thompson. ‘Two others, both males, 
though very unlike in general appearance, agree structur- 
ally for the most part with and are probably different stages 
of M. anglica, Lubbock. Examined with a high form 
(, Obj. Gundlach) these reveal some points apparently 
overlooked by other observers. The spines situated on 
the 2nd and 3rd joints of the antenne of the specimen 
which I take to be the more mature of the two have 
finely serrated edges (Pl. IV. fig. 5.) The fifth and apical 
seoments have one feathery plume on the inner side of 
each (fig. 3). The sete of the swimming feet and caudal 
segment are all finely plumose. The first abdominal seg- 
ment bears a symmetrical genital appendage curiously like 
the tail fin of a fish, (see fig. 6). It is a good deal differ- 
ent in form from Bourne’s fig. 9, though doubtless of the 
same nature and function—whatever that may be. 
The last specimen of Monstrilla which I have found 
differs entirely in several pomts from any hitherto des- 
cribed species. From its very long antenne I propose to 
name it Monstrilla lonyicornis, and describe it as follows: 
Monstrilla longecornis, n. sp. (Plate IV., figs. 1, 2, and 4). 
Length from apex of antenne to caudal segment 1-15th 
ofan inch. Antenne almost the same length as the entire 
cephalothorax, having six segments; the first and basal 
seoment as broad as long; the length of the second about 
four times as long as the width, bearing a spine about the 
centre on inner side and several spines near its apex; the 
third segment about twice as long as broad, bearing 
several spines; the fourth about the same length as the 
second, with an enlargement about the centre bearing 
spines. Between the fourth and the penultimate there is 
