COLLECTED IN CEYLON. 315 



Genus Btthocytheee, G. O. Sars. 



Bythoctthere EETtrsA, n. sp. (Plate XL. figs. 22-24.) 

 Shell, seen from the side, oblong, twice as long as broad, slightly 

 higher in front than behind ; anterior extremity rounded, poste- 

 rior obliquely rounded off below the middle, where it forms an 

 obtuse angle, obliquely truncated and emarginate above ; dorsal 

 margin straight, ventral gently convex : seen from below, tlie out- 

 line is ovate, twice as long as broad, widest in the middle ; extre- 

 mities strongly mucronate : end-yiew very irregular. The valves 

 are slightly papillose, have a deep transverse furrow near the 

 middle, and a sharp longitudinal crest in the middle line behind 

 the furrow, also in the middle of each ventral margin a promi- 

 nent curved ridge or ala, which ends behind in a sharp angle ; 

 anterior hinge-tubercle prominent ; ventral surface flat, keeled, 

 and longitudinally grooved. Length -g^g of an inch ("66 millim.). 



G-enus Paeadoxo stoma, Fischer. 



Paradoxostoma cikgalense, n. sp. (Plate XL. figs. 35, 36.) 

 Carapace compressed, oblong ; seen from the side, thrice as 

 long as broad, greatest height in the middle ; anterior extremity 

 depressed and rounded, posterior produced into a broad, obtuse 

 beak ; dorsal margin boldly arched, ventral sinuous : seen from 

 above, oblong-ovate, quite four times as long as broad, widest in 

 the middle and tapering evenly to the extremities, which are 

 sharply pointed. Surface smooth, without markings. Length 

 ■g^Y of an inch ("7 millim.). 



DESOEIPTION OF THE PLATES. 

 Plate XXXVII. 



Figs. 1-3. Limnadia Hislopi, Baird. 1. Entire auimal, magnified. 2. Head 

 and antennse, more highly magnified. 2 a. Serratures of anterior 

 part of head, still further enlarged. 3. Abdominal rami, also highly 

 magnified. 



Figs. 4 & 5. Moina submucronaia, n. sp. 4. Animal, seen laterally, magnified. 

 5. Abdomen, more highly magnified. 



Figs. 6-9. Ilyoci'yptus Halyi, n. sp. 6. Animal, seen laterally, magnified. 



7. Portion of upper branch of posterior antenna, more highly magnified. 



8. Abdomen, ditto. 9. Some of the spines of the abdomen, more 

 highly magnified. 



Figs. 10-15. Attheyella cingalensis, n. sp. 10. Anterior antenna of female. 

 11. Secondary branch of posterior antenna of same. 12. Foot of 



