708 CRETACEOUS PALEONTOLOGY. 



Family OBRITHIIDAE. 



Genus CERITHIUM Bruguiere. 

 .,,,_. Cerithium pilsbryi Whitfield. 



Plate LXXXL, Figs. 3-5. 



1893. Cerithium Pilsbryi Whitf., The Nautilus, vol. 7, pp. 38 



and 51, pi. 2, fig. 3. 

 1905. Cerithium pilsbryi Johns., Proc. Acad. Nat. Sci. PhiL 



(1905), p. 22. 



Description. "Shell elongate and slender; volutions numer- 

 ous, number not determined, very gradually expanding with ad- 

 ditional growth; apex and aperture unknown. Volution slightly 

 convex between the sutures, and ornamented by a band of small 

 oblique riodes immediately below the suture; also by a series of 

 larger vertical folds which extend across the exposed part of the 

 volution, below the upper band of nodes, and numbering some- 

 thing more than half as many to the volution as the nodes above. 

 There are also very fine spiral striae almost too fine to be seen 

 without magnifying. The lines of growth are fine but distinct, 

 and take a broad sweeping backward curve below the sutures." 

 (Whitfield.) 



The dimensions of one of the most complete individuals ob- 

 served, a specimen not complete to the aperture and with the apex 

 of the shell missing, are: height, 27 mm.; maximum diameter, 

 ii mm.; number of volutions showing 9, apical angle 23. A 

 specimen 18 mm. in length, with the apex nearly complete has nine 

 volutions. 



Remarks. This is one of the common species at Lenola. The 

 internal casts are rather loose coiled, with low, somewhat indis- 

 tinct vertical nodes, but not retaining any indication of the narrow, 

 nodose, revolving band seen at the upper margin of the volution 

 on the external surface of the shell. Good impressions of the 

 exterior of the shell are sometimes met with, and it is upon casts 

 taken from such natural moulds that the external characters of 



