1896.] NATURAL SCIENCES OF PHILADELPHIA. 11 



tiuctly flattened, though convex. Umbilicus somewhat exceeding 

 one-third the total diameter, broad, deep and perspective, the sutures 

 within it strongly impressed. 



Diameter 7 cm. ; width of last whorl at aperture (measured below) 

 26 mm.; alt. of same about 19 mm. 



The surface of the cast is smooth, not showing the impression of 

 the anal fasciole. The sinus was probably short, at least in compar- 

 ison with the large recent species ; but as the latter third of the 

 specimen is largely concealed by a hard arenaceous matrix, no im- 

 pression of the anal sinus can be made out. The unremoved matrix 

 shows clear impressions (external moulds) of the characteristic Lower 

 and Middle Marl bed species Plicatula urticosa Mort. and Ostrcea 

 larva Lam. 



In Pleurotomaria perlata Conr., the periphery is more strongly 

 keeled and the umbilicus narrower than in this species. In Pleuro- 

 trema solariformis Whitf. the whorls are flatter both outside and 

 within the umbilicus, and the slit is said to be bridged at intervals, 

 though this last feature is excessively obscure if present in the type 

 specimen. 



The specimen described above is the property of Henry L. Bal- 

 derston and has for the present been deposited in the museum of 

 the Academy. 



The type of Cirrus crotaloides Morton is a much smaller shell, 

 alt. 18, diara. 39 mm. It is an internal cast of whitish calcareous 

 material ("rotten limestone"). The last whorl has been broken 

 above near the aperture, and the whorls of spire are slightly distorted 

 on one side by pressure, and have lost considerable material by ero- 

 sion. The umbilicus is filled to its verge with a calcareo-arenaceous 

 matrix, harder than the cast itself, and a narrowly conic protuber- 

 ance of the same material projects over the apex. This has been 

 mistaken by Morton for the true spire, which accounts for his words 

 " the two first whorls [sic] suddenly produced." In reality the true 

 apex of the shell is concealed by this bit of hard matrix, about three 

 whorls being visible. The contour of the last whorl is practically 

 identical with that shown in the middle figure of the plate illustrat- 

 ing the Mullica Hill specimen. No impression of the anal sinus or 

 fasciole is visible on the cast. 



Erie, the locality Avhere Conrad collected the type of crotaloides, 

 is on the Black Warrior River, in the Selma Chalk or " Rotten 

 Limestone " member of the Alabama Cretaceous. 



January 21. 



The President, Samuel G. Dixon, M. D., in the Chair. 



Fifty-two persons present. 



Papers under the following titles were presented for publication : — 



