1890.] NATURAL SCIENCES OF PHILADELPHIA. 469 



identifies as Nerincea Goodhalli. The absence of the eolumellar 

 characteristics prevents jwsitive determiuatiou. 



Murex sp. indet. (Plate XIII, fig. 2). 



The drawing is from a tracing made on a polished marble which 

 shows the contour of the species perfectly, but unfortunately fails 

 to furnish the specific characters. I obtained a perfect specimen of 

 the same species in the Escamela quarry, but it was lost before I 

 had an opportunity to fully examine it. 

 Tylostoma'? (Plate XIII, fig. 1.) 



Two section-specimens of this large gasteropod were found in the 

 rocks of the Escamela quarry, from one of which the figure was care- 

 fully traced. The unequal balancing of the whorls and the some- 

 what irregular flow of the eolumellar surface would seem to indicate 

 that the specimen had undergone some little distortion. I am not 

 sure of the generic position of the shell, but it appears to be nearest 

 to Tylostoma or to Pterodonta, and it may not unlikely be the giant 

 Tylostoma (T. princeps) which Dr. White has described from the 

 mountains of Tehuacan (La Naturaleza, Mexico, 1883, p. ^20). 

 The casts (of Pterodonta inflata f) figured by Ramirez in his geolog- 

 ical report on the Sierra Mojada mountains (Anales del Ministerio 

 de Fomento, III, 1880) not impossibly represent the same species. 



Ostrea sp. indet. (Plate XIII, fig. 8). 



This is, without doubt, the oyster which has been referred to by 

 Barcena as Ostrea (Exogyra) virgula. It is certainly of the type of 

 that species, but yet it may equally represent one of the closely re- 

 lated Cretaceous forms, and is, perhaps, not far removed from Gabb's 

 Gryphea viiccronata ( G. Pitcher L) 



Caprina? (Plate XIII, fig. 7). 

 Ichthyosarcolithes ? (Plate XII, figs. 2, 3, 4, 5). 

 Hippurites sp. indet. (Plate XIV). 



This is by far the largest Hippurite which I found in the Mexi- 

 can rocks. I strongly suspect that it is the common European H. 

 comu-vacciniim, but the condition of preservation of the specimen 

 does not permit its specific affinities to be positively determined. 

 The drawing is traced from a polished marble. 



