250 BULLETIN OF THE 



Triforis (Sychar) cylindrella Dal^ 



Plate XX. Fig. 6. 



Triforis cylindrellus Dall, Bull. M. C. Z., IX. p. 83, 1881. 

 Habitat. Cape San Antonio, 640 fms. 



Family CERITHIOPSID^E. 



The existence of a retractile proboscis in Cerithiopsis and Seila is quite 

 ground enough, were there no other characters, for separating this group as a 

 family from the Cerithiidaz. 



Genus SEILA A. Adams. 



Seila A. Adams, Ann. Mag. Nat. Hist., VH. p. 130, 1861 ; type 5. dextroversus Ad. & 



Reeve. (China Seas.) 

 Viriola Jousseaume, 1884, not of Tryon, 1887. 

 Cinctella Monterosato, Nom. Conch. Medit., p. 123, 1884; type C. trilineatum Phi- 



lippi. (Mediterranean.) 



The close resemblance of S. dextroversa to the C. terebralis C. B. Adams, so 

 far as shell characters are concerned, is warrant in default of negative evidence 

 for combining the two forms in one group. The characters of C. terebralis, as 

 worked out by Stimpson and independently by myself, are sufficient to elevate 

 Seila to the rank of a genus, and separate it entirely from Cerithiopsis, of which 

 it has been regarded as a synonym. Jousseaume, whose work on Triforis I 

 have been unable to consult, would apparently, judging from Tryon 's remarks, 

 regard Seila as a dextral Triforis, but this is an erroneous assumption, as I 

 shall proceed to show, and the peculiar dentition and shell characters of Trifo- 

 ris are in my opinion a justification for according to it family rank by itself. 



Seila terebralis C. B. Adams. 



Cerithium terebrale C. B. Adams, Bost. Journ. Nat. Hist., III. p. 320, pi. iii. fig. 7, 

 1840. 



C. terebellum C. B. Adams, Cat. Coll., p. 19, note, 1847. 



Cerithiopsis terebellum Stimpson, N. Engl. Shells, p. 45, 1851. 



Cerithiopsis terebralis H. & A. Adams, Gen., I. p. 241, 1853. 



1 Cerithium trilineatum Pliilippi, En. Moll. Sicil., I. p. 195, pi. xi. fig. 13, 1836; Jef- 

 freys, P. Z. S. 1885, p. 61. 



Habitat in America. Massachusetts, southward to Florida and the Antilles. 

 ? Europe, in the Mediterranean, extremely rare. 



I have carefully examined Dr. Jeffreys's series of trilineatum, recent and fossil, 

 and do not feel that it justifies the consolidation. The fossil is a much more 



