PLATE X. 



Fig. 1. Fenestella multiporata? 274 



la. A portion of the polyzoum, showinp: the non-poriferous side. Natural size. 



16. A small portion of the same, maiinifled to show the surface strias, and the relative sizes 



of the fenestrules, branches, and dissepiments. 

 Ic. Poriferous side of same, to show the number and proportional size of the pores, with their 



prominent margins. 



Fig. 2. Feneste^^la delicata 273 



2a. A portion of the polyzoum, natural size, non-poriferous side. 



26. A .small piece of same magnified. 



2c. A small fragment, more highly magnified, to show small nodes and nearly obsolete striae 



on this side. 

 2d. Another fragment, still more highly magnified, to show the pores and subnodose mesial 



carina. 



Fig. 3. Productus ...-. 283 



View of ventral valve. 



Fig. 4. Productus 282 



4a. A side or profile view of cast of ventral valve. 



46. Front view of same. 



4c. Another view, the same specimen represented by fig. 4a, turned so as to show a cast of the 



interior of the dorsal valve and of the umbonal region, muscular impressions, etc., of 



the ventral valve. 



Fig. 5. Hemipronites ceenistria 279 



5a. A dorsal view of an internal cast, showing, obliquelj', the cardinal area, pseudo-del- 



tidium, etc. 

 56. A ventral view of same, showing cast of muscular scars. 

 5c. An outline lateral view of same. 

 5d. Surface striae -magnified to show the minute, regular lines of growth. 



