144 PROCEEDINGS : BOSTON SOCIETY NATURAL HISTORY. 
by one third. The other American representatives of the genus, 
A. auberiana d’Orb. and A. concinna C. B. Adams, do not extend 
north of Tampa, Fla. It certainly is not common and appears to 
be very highly local, which would explain why a shell so conspic¬ 
uous for everything but size has been so overlooked. If, as has 
been suggested (Cooke, ’95), the presence of haemoglobin in the 
buccal mass is correlated with special muscular activity in those 
parts, this Assiminea should prove a real glutton. The animal 
proves itself very active on occasion. 
Triforidae. 
Triforis perversa (Linne) var. nigrocincta (Adams). Verrill 
(’73), p. 648. Cerithium n. Smith and Prime (’70), p. 394. S. 
Uncommon. Under stones between tides. Locally on oyster 
beds. Dali makes it a variety of the European species. The pro¬ 
toconch of four whorls covered with a delicate yellowish red epi¬ 
dermis is unusually regular and no reminiscences of a dexter habit 
were detected. 
Cerithiopsidae. 
Cerithiopsis greenii (C. B. Adams). Verrill (73), p.647. Ceri¬ 
thium g. Smith and Prime (’70), p. 394. S. 
In September of 1899 one cast of the dredge on oyster beds 
brought up this species alive to the number of ten, the only occasion 
on which it occurred. With it were the young of Sella terebralis 
and adult specimens of Triforis in considerable numbers. This 
brilliantly colored little shell is a beautiful microscopic object. The 
three smooth, swollen, and irregular whorls of the protoconch, which 
are set over out of the axis of the shell, are succeeded by two 
whorls in which the adult beaded sculpture is gradually established, 
first appearing not as connected beads but as disconnected rings. 
Sella terebralis (C. B. Adams). Cerithiopsis t. Verrill (’73), 
p. 648. C. terebellum Stimps. Smith and Prime (’70), p. 397. S. 
Common alive on piles and Ulva, and (mostly dead) on shelly 
bottom. Young of 2.2 mm. taken in the middle of September 
show a protoconch of three swollen yellowish white whorls suc¬ 
ceeded by a whorl showing distinct reminiscences of a beaded 
sculpture, after which the regular corkscrew pattern comes in. 
