RECENT BRITISH OSTRACODA. 



373 



in front, the greatest breadth equal to less than half the length. End view oval. The 

 surface of the shell is highly polished and marked by closely set longitudinal anasto- 

 mosing striae (fig. 10). Colour dark brown. The anatomical structure agrees closely 

 with that of C. compressa. 



Length in., height 5^ in. ^ 1, Vvw > ^ 



Hab. Greenlea Lough, Nortliumberland ; Mickle Fell, Yorkshire j Connemara (G. <S. B.) ; Lochmaben 

 {Sir W. Jardine, Bart.) ; Peterhead Canal {Mr. D. Robertson). 



The form described by me {loc. cit.) as a distinct species under the name of C. striolata, 

 is noticed by Dr. Zenker as a variety of C. punctata [compressa) ; but the diflFerences in 

 size and surface-marking are so conspicuous as to form good specific characters ; more- 

 over the shells of the two species seem to retain their distinctive characters in all 

 stages of growth. Dr. Zenker conjectures, but scarcely believes, that C. striolata may 

 possibly be the very old state of C. compressa, inasmuch as he has never met with it 

 except in the adult condition. I have, however, seen both young and old indi- 

 viduals, always retaining the distinctive characters of shell-sculpture &c. Cypris prasina, 

 Pisch., and C. exscnlpta, Piscli. (Munich Transactions, Band xvii.), bear some resemblance 

 to the present species in their surface-marking; but the general form of the carapace 

 seems to differ in both cases. 



18. Cypris ovum (Jurine). (Plate XXIV. figs. 31-34, 43-45, and Plate XXXVI. fig. 8,) 



Monoculus ovum, Jurine, Hist, des Monocles, p. 179, pi. xix. figs. 18, 19. 

 Cypris minuta, Baird, Brit. Entom. p. 155, tab. xviii. figs. 7, 8. 



Valves subreniform, convex, greatest height equal to two-thirds of the length. 

 Anterior and posterior margins rounded and nearly equal. Ventral margin distinctly 

 sinuated near the middle; dorsal boldly arched, sloping more steeply behind than in 

 front. Seen from above, the outline is ovate, widest behind the middle, broadly rounded 

 behind, and tapering to a subacute extremity in front : greatest width equal to more 

 than half the length. End view very broadly oval. Surface of the shell smooth or 

 slightly punctate, sometimes slightly hispid. Colour yellowish or olivaceous brown, with 

 irregular dark cloudings and transparent patches. The animal is almost precisely similar 

 to that of C. Icevis — two of the filaments of the second antennae excessively long, the 

 rest very short. The males, of which I have seen only one imperfect specimen, have the 

 second jaws chelate. 



Length 5V in., height 7^ in. .4'i"^\v \ .fb 



This species is very common and widely distributed ; but, as I for a long time supposed 

 it to be a form of C. Icevis, I am unable to specify exactly all the localities in which I 

 have noticed it. The two species occur very generally in company with each other, but 

 sometimes separately. The specimens from which my illustrations are drawn were 

 taken at Axwell Park, in the county of Durham. Eigs. 43-45 are more highly magnified 

 representations of a form taken by me in the Loch o' the Lowes, Selkirkshire, perhaps 

 the young of the present species, though the lower antennse bore only one long seta. 



