INSTITUTE OF SCIENCE, PHILADELPHIA. 299 



This elegant little shell is quite distinct from any of the figured species, 

 recent or fossil, with which it has been carefully compared. 



Cascum regulare Carpenter. 

 C. regulare Cpr., P. Z. S. 1S58, p. 16, No. 22. 



Pliocene of the Caloosahatchie, Alligator Creek and Shell Creek, Dall 

 andWillcox; living in the Antilles, at Singapore and in Australia. This 

 species was identified by the Marquis de Folin from specimens sent him by 

 Carpenter, and agrees with others named by Carpenter in the National col- 

 lection. It is much smaller than C. floridanum, and has numerous rather dis- 

 tant rings, with a flattish plug having a small, sharp subcentral mucro. 



Csecum Cooperi S. Smith. 



C. Cooperi Sanderson Smith, Ann. Lye. N. Hist. N. Y. vii. pp. 154, 16S, 1862 ; ibid. ix. p. 



393. fig- 3. 1870 ; Tryon, Man. viii. p. 221, pi. 67, figs. 84, 85 ; not of Caipenter. 

 C. Sfnithii Cooper, Proc. Acad. Nat. Sci. Phila. 1872, p. 154. 

 C. costdtum Verrill, Am. Journ. Sci., 3d Sen, iii. p. 283, pi. 6, fig. 6, 1872. 



Newer Miocene of the Cape Fear River, N. C, at Mrs. Guion's 

 marl-pit, Johnson ; Pliocene of Shell Creek, Florida, Willcox, and of the 

 Caloosahatchie, Dall ; living from Vineyard Sound, Mass., to Florida and the 

 Antilles. 



The Marquis de Folin observes that this differs from C. imbricatum 

 Cpr. of the West Indies by being longer, more conical and having more 

 strongly marked sculpture. The specimens of C. ijnbricatuvi given by Dr. 

 Carpenter to the National collection are much more arched in their curve 

 and relatively more slender. 



The species named C. Cooperi by Dr. Carpenter from California is of 

 later date, and the change of naine must apply to it and not to the Eastern 

 shell. It is observable on this species, and in nearly all the others which I 

 have examined, that, judged by the longitudinal ribs, most of the specimens 

 are slightly twisted, the amount of twist being variable, but giving evidence of 

 an atavistic tendency which they have not yet been able wholly to overcome. 



Csecum californicura Dall. 



C. Cooperi Cpr., Rep. Brit. Assoc. 1864, p. 655 ; not of Smith. 



C. californicum Dall, Proc. U. S. Nat. Mus. 1885, p. 541 ; Tryon, Man. viii. p. 219, pi. 66, 

 fig. 65, 1886. 



Pliocene of Lower California at San Quentin Bay, C. R. Orcutt ; Post- 

 Pliocene of Coronado beach, San Diego, Cal., Steai'ns; living on the coast 

 of California at San Diego, Cooper, Orcutt, etc. 



This is a finely annulated, compact species, with a slightly contracted 

 aperture. 



