1912.] NATURAL SCIENCES OF PHILADELPHIA. 503 



crabs, in the lower layer. It was in these lignitic layers that the 

 oxidation of pyrite produced a heating of the shale, resulting in 

 the generation of steam and gas that was reported in the daily 

 press as the breaking out of a volcano in the Culebra Cut. The 

 fossils are largely pseudomorphs of calcite, and when they are 

 wetted the shell crumbles and falls apart. It is very difficult to 

 clean the shells in this bed from the adhering shale on this account. 

 The number of species is considerable, but only a few can be 

 extracted in sufficiently clean condition to be determined or 

 described. A list of the species that could be studied is given 

 below : 



Species observed in the Pecten Bed at Tower N, Las Cascades. 



Balanus sp. 



Murex (Phyllonotus) gatunensis B. and P. 

 Pyrula micronematica n. sp. 

 Area sp. 



Pecten (Amusium) sol n. sp. 



Pecten (Amusium) sp. indet. A fragment of an Amusium with 

 even ribs. 



Pecten (Mquipecten) oxygonum canalis n. subsp. 



Ostrea gatunensis B. and P. 



Tellina vetula n. sp.- 



Semele chipolana Dall. 



Chione (Lirophora) ulocyma (Dall.). 



Dosinia delicatissima n. sp. 



Crassitellites mediamericanus n. sp. 



Kuphus incrassatus Gabb. 



Schizaster schertzeri Gabb. 



Species observed in the Lignitic Layers near Tower N, Las 



Cascades. 



Callianassa scotti n. sp. 



Nassa (Hi ma) prceambigua n. sp. 



Bittium scotti n. sp. 



Turritella altilira Conrad. 



Area dalli n. sp. 



Spondylus scotti n. sp. 



DESCRIPTIONS OF NEW SPECIES. 

 Callianassa scotti n. sp. PI. XXII, figs. 1-3. 



The propodite is quadrate, its width nearly or quite equal to the 

 length, the upper face evenly convex, its surface granular, at least 

 near the base of the fixed finger. The proximal margin is abruptly 

 33 



