ON A BARE BRITISH ENTOMOSTRACON. 



two spines. Perhaps the most marked feature of the animal is the 

 bristles with which the edges of the carapace valves are fringed. These 

 are set in an unbroken row from just below the mandibles to the 

 junction of the valves behind. They are flexible, rather stiff, and 

 branched but not plumose, varying in length from about 1-500" along 

 the front of the body to about half that size along the posterior edge. 

 The abdomen bears as usual one pair of mandibles, («,) five pairs of 

 branchial limbs, (p. 1 — 5,) and a very large post-abdomen (g) terminating in 

 two long rather straight hooks. This part of the body is larger than in 

 any other species of the family with which I am acquainted, and is 

 capable of a very wide range of motion, at times being extended 

 quite outside the valves of the carapace, 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 each 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 setae (/) are situated. These 

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

 are sparsely 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 carried by the 

 female until hatched. I could not make out this spine very distinctly. 



The branchial legs, (Plate I., p. 1 — 5.) ten in number, are largely 

 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 setae, 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 carapace. Indeed, the ends of these two sets of setaB 

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

 which. The intestinal canal presents no peculiarities, being almost 

 straight. 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 alive) with those given 

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

 in two points from the "orthodox" Hyocryptus 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 typical species, the setae which fringe the carapace arc 

 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 



