394 TWENTIETH REPORT ON THE STATE CABINET. 



Illcenus (Bumastus) worthcnanus. W. and M., pa. 105 (not figured), and 

 Acidaspis ida^ W. and M., pa. 106. I have already commented upon these 

 species on page 389. 



Porcellia senex, W. and M., pa. Ill, pi. iii, f. 6. 



*' Shell small, consisting of one and a half or two very rapidly enlarging, 



"detached whorls, which are somewhat oblique in the young shell, but 



" afterwards continue very nearly in one plane. Toward the aperture 



" the shell is flattened and subnodulous on the dorsum." 



The specimen is a cast of the interior of a Platyceras, closely allied 



to P. niagarense; and the spire is oblique throughout its entire extent, 



the two sides of the shell being nowhere symmetrical. There are a few 



undulations on the back, from inequalities of growth at the aperture, 



which has been deeply sinuate ; but there is no evidence of the narrow 



carina on the dorsum, or slit at the aperture, characteristic of Porcellia. 



