1887.] NATUEAL SCIENCES OF PHILADELPHIA. 37 



taceous rocks of the State of Puebla, Mexico, which is probably 

 congeneric with this Texan form. It is probable also that the 

 GervUlia Renaxixiana of Matheron, and other published forms, 

 ought to be referred to the genus here proj^osed. A form from 

 the Cretaceous of Brazil, described by me some years ago under 

 the name of GervUlia dissita, but still unpublished, seems to 

 belong to this genus. If those species should be assigned to this 

 genus it may be that the crenulation of the hinge will be found 

 to be an inconstant character; but the other characters which are 

 herein described are regarded as a sufficient basis for its generic 

 identity. 

 Aguileria Cumminsi (sp. nov.). PI. II, figs. 1-3. 



Shell inflated, obliquely subelliptical in marginal outline; test 

 thick, hinge line moderately long; hinge areas broad, bearing 

 three or four ligamental pits; hinge border including the surface 

 of the cardinal teeth, distinctly crenulated in adult examples; 

 posterior cardinal tooth moderately large; anterior one small 

 and indistinct. 



EXPLANATION OF PLATE II. 



Aguilei-ia cumminsi White. 



Fig. L Left side view of an adult example. 

 Fig. 2. Dorsal view of the same. 



Fig. 3. Interior view of a left valve, somewhat narrowed by lateral 

 compression, showing the hinge and cardinal area. 



Dalliconcha invagiiiata W. 



Fig. 4. Right side view of a restored outline, reduced to three-fourths 



natural size. 

 Fig. 5. Front view of an adult example, restored as to its outline from 



a partially crushed condition. 



Dalliconcha ensiformis Conrad, sp. 



Fig. 6. A left valve, showing hinge and front features ; introduced for 

 comparison. 



Stearnsia robbinsi W. 



Fig. 7. Left side view of a medium-sized example. 



Fig. 8. Dorsal view of the same. 



Fig. 9. An imperfect example, showing the hinge of the left valve. 



All the figures except 4 are of natural size. 



