244 BULLETIN OF THE 



the large pale-tubercled Mediterranean variety from the small British variety 

 adversa Montagu, and cannot be claimed as of more than varietal importance. 



The British shell is usually more solid and uniformly dark, but there are 

 paler individuals with dark base, differing from typical nigrocincta only in be- 

 ing a little heavier. But nearly all British individuals are heavier than those 

 of the same species from the American shores. The sculpture of many of the 

 British individuals is a little coarser, and they probably average a little bigger 

 than American specimens. 



The variety nigrocincta is usually brown with a dark brown base ; this shin- 

 ing through the sides of the shell below the suture gives the effect of a brown 

 presutural band. Individuals in which the base is no darker than the sides 

 do not show it. T. modesta C. B. Adams is a small uniformly dark specimen, 

 and his T. intermedia is (from a typical specimen) a form in which the middle 

 spiral has its nodules paler colored than the rest of the shell. 



Two or three genera or subgenera have been founded on this species, as hav- 

 ing the canal open and the whorls flattened, but the canal is often closed in 

 both foreign and American specimens, and the form is precisely that of Masto- 

 nia, sometimes flattish, but most generally moderately inflated and fusiform. 



Triforis decorata C. B. Adams var. olivacea Dall. 

 Cerithium decoratum Adams, Contributions to Conch., p. 177, 1850. 



Habitat. Gulf of Mexico, west of Florida, in 50 fms. Key West, Hemp- 

 hill. Antilles, Adams. 



This species does not show the anal notch tubular when perfectly adult, con- 

 sequently it should not be placed in the typical section of Triforis, as has been 

 done in Mr. Tryon's Manual. It is closely related to T. ornata of Deshayes. 



The Floridian specimens are of a more olive and brown tendency, and are 

 also larger and have a greater proportional diameter than the types of Adams 

 or any of the Antillean specimens I have seen. The latter all tend to a macu- 

 lation of blackish brown and white, are smaller, and more slender. The dis- 

 tinction seems of varietal importance, though it would, doubtless shade off 

 imperceptibly in a full geographical series. 



B. Apical nucleus swollen, mammillary . 

 Triforis turris-thomas Orbignt. 



Triforis turris-thomoz (Chemnitz) Orb., Moll. Cub., II. p. 155 (pi. xxiii. figs. 10-12 f), 



1842. Dall, Bull. M. C. Z., IX. p. 81, 1881. 

 Triforis intermedins Tryon, Man., p. 188, 1887, not of C. B. Adams, 1850. 



Hab'itat. Station 2, 805 fms., one dead specimen, probably drifted from 

 ehoaler water. Reported by Orbigny in shell sand from Cuba and Guadelupe 

 Island. 



