PLATE XXXII. 

 Mesothyra Ooeani. 



Pnge 187. 



Fig. 1. An outline restoration <lt:i\vn from the large right valve represented on plate 33, fig. 4, showing 

 the probable character of the articulation of the valves of the carapace, the position and rela- 

 tive size of tlif rostral and dorsal plates, the number of abdominal segments and the setiferous 

 caudal spines. 



Pig. 2, The optic node of the specimen represented on plate 33. fig. 4. enlarged to three diameters, show- 

 ing the deep circular ]>it at its summit. 



i \ similar enlargement of the optic node of the valve shown on plate 33. fig. 5. 



I 4. A portion of the carina on the valve represented upon plate 33, tig. 4. enlarged to three diameters. 



The lateral slopes arc divided by a sharply impressed longitudinal line into a punctate lower 

 portion an«l an impunctate, gently crenulated summit. 



Fig. .">. A portion of the right cei pod of the post-abdomen shown on plate 34. fif,'- 4. enlarged to threi 



diameters ; showing the impressions of the setse, their bases of attachment along the inner 

 margin of the spine and the coarsely tubercled and ridged surface. 



Pig, 6. The hinge angle of the right valve figured on plate 33, fig. 4, enlarged to three diameters ; show- 

 ing the thickened apex, curved upward and inward for articulation with the left valve, and the 

 tubercled and punctate surface. 



Mesothyra Xeptuni. 



Page 191. 

 Fiu r . 7. A portion of the light cercopod of the specimen represented on plate 33. fig. 1 ; drawn to show 

 more distinctly the character of the surface ornamentation. 

 Hamilton group. Plainfield, Otsego county. 



Mesothyra spum^ka. 



Page 193. 



Pig. s. ,\ nearly entire caudal spii f this species. 



Fig. 9. A portion of tin- same, enlarged to three diameters, to show tho character of the surface ornamen- 

 tation. 



Hamilton group. Delphi, Onondaga county. 



