1870.] BRADY— ON BIVALVE CRUSTACEANS. 383 



of which only a poor specimen occurs, and may perhaps belong to 

 some other member of the genus. 



CytJierura undata, Sars, var. 

 A specimen which I suppose to belong to C. undata differs 

 enoudi to make it worth while in fisrure it. The difference is 

 chiefly in surf\ice-sculpture, but slightly also in outline. 



Cytherura pumila, C, B. & R., and Cytherura concentrica, 



C, B. &R. 



These species have already been figured and described (in MS.) 

 by the author in conjunction with Messrs. Crosskey and Robert- 

 son, from fossil post-tertiary specimens ; and I have not thought 

 it right here to forestall those descriptions, the publication of 

 which I hope may not be long delayed. 



Cytlierideis foveolata, nov. sp, (Figs. 1--3. 

 Carapace elongate, compressed; seen from the side, siliquose, 

 slightly depressed in front ; greatest height situate about the 

 middle, and equal to rather more than one-third of the length ; 

 extremities rounded, the anterior much the narrower; superior 

 margin almost straight, inferior slightly sinuated in the middle. 

 Seen from above, elongate ovate, widest near the middle, 

 tapering gradually toward the front, more abruptly behind; 

 extremities acuminate ; width equal to one-third of the length. 

 Shell surface smooth, minutely and somewhat densely punctate, 

 semitransparent, horny. Length -gV inch. 



Nearly allied to C. suhidata^ Brady, but more robust and 

 more densely punctate. 



EXPLAJfATIOX OF PLATE OF RECENT OSTRACODA FROM 

 THE GULF OF ST. LAWREIS^CE. 



Fig. L Cytherideis foveolata, carapace, seen from the left side. ) 



Fig. 2. The same, seen from above. V x 40. 



Fig. 3, The same, seen from below, J 



Fig. 4. CytJicre canadensis, carapace, seen from the left side. ^ 



Fig. 5. The same, seen from above. > s 50. 



Fig. 6. The same, seen from the front. ) 

 Fig. 7. Cytherura undata, var., carapace, seen from the left side, x 84. 



Fig. 8. Cythere Dawsoni, carapace, seen from the left side. ) 



Fig. 9. The same, seen from above. \ x 50. 



Fig. 10. The same, seen from below. ) 



Fig. 11. Cythere Icioderma, carapace, seen from the left side. ) 



Fig. 12. The same, seen from above. ', x 40. 



Fiy. 13. The same, seen from behind. ) 



