INSTITUTE OF SCIENCE, PHILADELPHIA. 267 



Superfamily CERITHIACEA. 



Family CERITHIOPSID/E. 



Genus SEILA A. Adams. 



This genus is well separated from the genuine Cerithiopsis by characters 

 found in the soft parts, as well as by the spiral ribbing which seems to char- 

 acterize the shells. The animal (of 5. Adaiiisii) has a short, broad foot, in- 

 dented in the middle line in front, with a square-edged mentum nar- 

 rower than the foot and extending beyond it; the operculum is shaped like a 

 Carinaria shell in outline, but somewhat narrower, with the apex free, pointed 

 and turned to the left. The attached surface of the operculum is deeply con- 

 cave, so that in some old specimens it seems hollow. The tentacles are very 

 short and stout, the proboscis seldom protruded ; there is no muzzle like that 

 of Cerithhitn. The jaw is composed of spade-shaped, rather large, close-set 

 horny plates, the points projecting. The rhachidian tooth is sub-rectangular, 

 wider than high, with two widely separated, strong, sharp cusps, and a much 

 feebler, shorter and smaller one in the middle line between them. The major 

 lateral is oblong, not very much wider than high, and has a strong recurved 

 cusp with one large and one small denticle ; the outer laterals, higher than 

 wide, have two denticles at the point, which is less than half as wide as the 

 base; formula | + |-- \ •■j + f' 



The group appears to have an ancient lineage. Ceritliiopsis moreauensis 

 Meek from the Cretaceous seems to belong to it, while C. constricta H. C. Lea 

 represents it in the Eocene, C. clavidiis H. C. Lea and C. annulatuvi Em- 

 mons in the Miocene ; C. Adamsii Lea in the Pliocene, Post-Pliocene and re- 

 cent seas. Cinctella Monterosato, 1884, is a synonyme of Sella Adams, 1861, 

 but Loveiiella Sars, 1878, and Lceocochlls D. &. M., 1874, are separated by 

 good anatomical characters, the latter being nearest to Sella. 



Sella AdamsU H. C. Lea. 



Cerithium Emersoiiiivar. C. B. Adams, Boston Journ. N. Hist. ii. p. 285. 



Cerithium terebrale C. R. Ads., Boston Journ. N. Hist. iii. p. 320, pi. iii. fig. 7, 1S40; 

 Gould, Inv. Mass., 276, fig. iSi, 1841 ; H. C. Lea, Am. Journ. Sci. xlii. p. io5, 1842 ; De 

 Kay, New York Moll., p. 130, pi. viii. fig. 172, 1843 ; not of Lamarck. 



Cerithium Adamsii H. C. Lea, Trans. Am. Phi). Soc, 2d Ser. ix., extras p. 42, 1845. 



Cerithium terebellum Adams, Cat. Coll., p. 19, 1847 ; Sowerby, Thes. ii. p. 880, pi. clxxxiv. 

 fig. 241, 1S55. 



Cerithiopsis terebellum Stm., Sh. of New Engl., p. 45, 1851. 



Sella terebrans Dall, Bull. U. S. Nat. Mus. No. 37, p. 138, pi. 52, fig. 5, 1889. 



Cerithium annulatuin Emmons, Geol. Rep. N. C.'ir., p. 269, fig. 161, 1858. 



? Cerithium clavulus H. C. Lea, Trans. Am. Phil. Soc, ix., extras p. 42, pi. 37, fig. 89, 1845. 



Older Miocene of the Chipola beds, Florida, Burns; Newer Miocene of 

 Virginia and North Carolina, Lea, Emmons ; Pliocene of the Croatan beds of 

 North Carolina, of the Waccamaw beds of South Carolina, the Caloosahat- 



