ON A RARE BRITISH ENTOMOSTRACON. 63 



capable of a very wide range of motion, at times beiii» extended 

 quite outside the valves of the cai'apace, backwards, at other times 

 thrust upwards within the carapace till the end touches the 

 antennules. 



Along the lower edge of the post-abdomen are four rows of curved 

 spines, two on aach side of the median line, the inner rows being rather 

 smaller than the outer. All the rows converge posteriorly and meet at 

 the point where the two post-abdominal setri) (/") are situated. These 

 last are excessively long, almost equalling the body in length, and 

 are sparseh' plumose along the distal half of their length. Posteriorly 

 the post-abdomen is provided with a rather blunt spine, (/(,) which serves 

 to keep the eggs in the open space, (o,) where they are cai-ried by 

 the female until hatched. I could not make out this spine verj^ 

 distinctly. 



The branchial legs, (Plate I., p. 1 — o,) ten in number, are largelj- 

 developed, the two lower pairs at least being expanded into great fan- 

 like paddles. Their surface is still further increased by very long 

 delicately-plumose setre, which spring, apparently, from the fold of 

 integument between the two terminal joints, and extend far beyond 

 the edge of the paddle, often projecting as far as the ends of the setae 

 which fringe the cai-apace. Indeed, the ends of these two sets of setas 

 are so mixed up as to make it rather difficult to determine which are 

 which. The intestinal canal presents no peculiarities, being almost 

 sti-aight. There were no ova in my specimen, and from this, its small 

 size, and relative transparency, I concluded that it was immature. 



Upon comparing the above description and figure (which were 

 compiled from notes made while the animal was ahve) with those given 

 by Norman and Kurz, it will be seen at once that my specimen differs 

 in two points from the "orthodox" Ihjocrijptus sordidus; but I do not 

 feel justified in founding a new species on grounds which, although 

 they might fairly entitle it to rank as a variety, are only matters of 

 detail, and require confirmation, such as can be obtained only by the 

 examination of numerous specimens. 



In the tj-pical species, the setjB which fringe the carapace are 

 plumose along the front or ventral edge, but along the lower or 

 posterior edge are branched, or, as Kurz expresses it, " one-sidedly 

 feathered," (see Fig. 2,) but in mine they are of the same character all 

 round the carapace, (Fig. 1.) Again, in the typical species, several of 

 the setae of the antennae are plumose, but in mine they are all bare 

 bristles. These setae, too, in mine are far longer than in the figures 

 given by Norman and Kurz. In Fig. 1 they are cut short by the 

 " inexorable limits of space." They should be continued in imagina- 

 tion about another inch, and the same remark applies to the post- 

 abdominal setae, (f.) 



With regard to the first point of difference, I would suggest the 

 possibility, from the confusion which exists among them, of the setae 

 belonging to the branchial feet, which are plumose, having been 



