Distribution of the British Ostracoda. 51 



The chief point of interest here is the occurrence of several 

 species which we have been accustomed to regard as inhabi- 

 tants of brackish water only, and of some (viz. Candona dia- 

 phana, G. Kingsleii, Metacypris cordata, and Darwinella Ste- 

 vensoni) which we had previously supposed to be limited to 

 the subbrackish fens and rivers of the East-Anglian district. 

 We have, however, but little knowledge of the contents of our 

 inland waters ; and it is quite probable that further research 

 may very much modify our views as to distribution. Mean- 

 time it may be noted that the Irish specimens of Metacypris 

 and Darivinella are of very poor growth and very scanty in 

 point of numbers. 



Cypris tessellafa, Fischer. 



The specimens which we doubtfully refer to this species, 

 though almost exactly similar to English examples in outline, 

 are considerably smaller, and the shell is very vaguely sculp- 

 tured, exhibiting only an approach to the characteristic tes- 

 sellation of the typical form. This peculiarity, however, we 

 have previously observed in young specimens, and even to 

 some extent in adults from certain localities ; and it would 

 not of itself have led us to doubt seriously the identity of the 

 Irish specimens but for a concurrent difference in the post- 

 abdominal rami, which are long and slender, slightly ciliated 

 on the inferior margin, and have the three terminal claws or 

 setse almost close together, the first seta being short, the second 

 about three times as long as the first, and the third nearly 

 twice as long as the second : the small seta usually found near 

 the middle of the lower margin is Avanting. The lakes in 

 which these specimens occm-red are Loughs Inagh and Cool- 

 barreen. 



Metacypris cordata, B. & R. PI. II. figs. 9, 10. 



Originally described from the shell only. We are now able 

 to add a definition of the contained animal, which belongs di- 

 stinctly to the family Cytheridas. 



Superior antennse slender, six-jointed, the third, fourth, and 

 sixth joints nearly equal in length, fifth slightly longer, last 

 joint bearing four slender setse, two of which are moderately 

 long ; fourth and fifth joints also bearing two or three slender 

 apical setffi ; inferior antennae, mandible, jaw, and feet as in 

 Cy there, the mandible-palp, however, short and indistinctly 

 jointed ; abdomen ending in two short curved setse. 



Hab. Lough Aubwee, near Galway. 



4* 



