30 \ REVISION OF THE BBITI8H SPECIES OF 



1889. Diaptomus graciloides, De Guerne & Richard (62), p. 36, 



pi. L, figs. 26, 27. 

 1889. ,, gracilis, De Guerne & Richard (62), p. 14, 



pi. II., figs. 12, 16, 20. 

 ( ? Glaucia hyalina, G. ccvsia, G. ovata, Koch.) 



Female. — Body slender ; cephalothorax widest in the middle, 

 and only slightly tapered towards either extremity; angles of 

 the last segment much produced and mucronate ; the first ab- 

 dominal segment bearing near the middle of each side a similar 

 but more slender spine : caudal lamina) short, seta3 very diver- 

 gent. Anterior antenna) very long and slender, when reflexed 

 reaching considerably beyond the extremity of the caudal lam- 

 ellae. Outer branch of the posterior antennaa much longer than 

 the inner, its last joint equal to half the length of the branch. 

 Outer branch of the fifth pair of feet three-jointed, terminal 

 process of the second joint stout, more or less bent; last joint 

 small, rather indistinct, quadrate, bearing two apical setaa, the 

 inner and larger of which nearly reaches the extremity of the 

 claw of the preceding joint, while the outer forms only a minute 

 spine: inner branch two-jointed, nearly as long as the first joint 

 of the outer branch, bearing at the apex two or three delicate, 

 translucent seta). Colour variable ; whitish, bluish-grey, or 

 brown. Length 1*3 mm. 



Male. — Angles of the last thoracic segments mucronate, slightly 

 produced backwards but not at all laterally; caudal seta) ad- 

 pressed. Antepenultimate joint of the right anterior antenna 

 usually produced externally at the apex into a blunt hatchet-like 

 process. Inner branch of the right fifth foot, one-jointed, stout, 

 reaching nearly to the extremity of the last joint of the outer 

 branch ; terminal claw of the outer branch strongly curved, fal- 

 cate or S-shaped : last joint of the outer branch of the left side 

 bearing at the apex a rather long sub-acute process and a lesser 

 spine-like appendage, and at the middle of its inner margin a 

 papilliform process, which has an apical brush of hairs. (PI. XI., 

 fig. 9a.) Inner branch one-jointed. The second joint of the 

 basal portion of the limb has its inner margin produced into a 

 keel-like flange, which ends abruptly in a rectangular promi- 

 nence beyond the middle of the joint. 



95 



