364 



MR. G. S. BRADY'S MONOGRAPH OF 



by the animal itself. And I feel no hesitation in uniting C. aurantia and C. rubra, as 

 all the gatherings I have seen contain both tuberculated and non-tuberculated specimens. 



8. Ctpris virens (Jurine). (Plate XXIII. figs. 23-32, and Plate XXXVI. fig, 1.) 



Monoculus virens, Jurine^ Hist, des Monocles, p. 174, pi. xviii. figs. 15, 16. 

 Cypris tristriata, Baird, Brit. Entom. p. 152, t. xviii. figs. 1, \a-i, 2, 3. 



virens, Lilljeborg, Crust, ex ord. tribus, p. 117, tab. viii. fig. 16, tab. ix. figs. 4, 5, tab. x. figs. 23-25, 



tab. xii. fig. 5, tab. xix. fig. 8, tab. xxvi. fig. 8. 



Valves oblong, reniform ; the extremities rounded and nearly equal. Dorsal margin 

 evenly arched, highest in the middle; ventral gently sinuated. Seen from above the 

 shell is oblong, ovate, pointed in front, rounded and narrow behind. End view broadly 

 oval. The surface is smooth or slightly pubescent and mostly marked with minute and 

 closely set puncta. The colour varies from a light greenish drab to a grass-green, varied 

 with strise of a deeper hue running obliquely across the valves from above downwards 

 and backwards. The lucid spots are large, oblong, irregular in size and shape, but 

 mostly somewhat crescentic or sinuous in outline. They are arranged in a group of 

 about seven, near the centre of the valve, and point obliquely from above downwards 

 and backwards. Besides the main group, isolated spots often occur on other parts of 

 the valves, especially near the dorsal margin. The two claws of the postabdominal rami 

 are unequal in length, and in fine specimens are serrated on their inner edge towards 

 the apex. The short seta on the inner margin of the ramus is not far removed from the 

 terminal claws. 



Length y^^- in., height 2V ' ' ^ ' ' ' 



Cypris virens is a very common species, met with mostly in small ponds, and appa- 

 rently very generally distributed throughout Britain and the continent. Like C.fusca 

 it seems seldom to inhabit lakes or large sheets of water. The hingement of this species 

 is a good example of the normal structure of the joint in Cypris. It is figured at Plate 

 XXIII. figs. 28, 29. 



4. Cypris obliqua, n. sp. (Plate XXIII. figs. 33-38.) 



Valves oblong, subreniform, not quite twice as long as broad. Extremities rounded 

 and nearly equal. Dorsal margin gently and evenly arched, highest in the middle ; 

 ventral margin nearly straight, slightly sinuated near the front. The dorsal aspect is 

 oblong-oval, broadest in the middle and tapering to the extremities, the anterior of which 

 is more sharply pointed than the posterior. End view oblique, the right valve being on 

 a higher plane than the left. Lucid spots nearly like those of C. virens. The surface 

 of the shell is shining, very slightly hairy, and thickly impressed with rather large 

 rounded puncta. Colour deep green or olive-brown, with three or four oblique darker 

 bands. Postabdominal setse stout and crowded together. — one long, two shorter and 

 nearly equal, the uppermost very short. 



Length 2V ^^-^ height ^ in. \ ' - . ^ , . . 



I first took C. ohliqiM in Loughrigg Tarn, Westmoreland, in the summer of 1861, and 

 for a considerable time thought it to be a very fine variety of C.fusca. Last year (1864), 



