DALL] REVIEW OF AMERICAN VOLUTID&. 363 
Shell resembling some of the varieties of brasiliana and ancilla, 
with variegated zigzag brown markings on the last whorl, but in 
which, according to Lahille, the young shell is so different from that 
of any of the other species that it cannot be properly united with 
any other. The young shell reaches a length of two and one fifth 
inches, with a diameter of one and three fifths. It usually has three 
plaits of which the anterior is less prominent than the third. The 
adult measures over seven inches long and about three and a half 
in diameter. A shell of this size weighed 260 grams, while a speci- 
men of ancilla var. teniolata Lahille, of exactly the same dimensions, 
weighed only 154 grams. 
I have not seen specimens of this species. 
ADELOMELON STEARNSII Dall 
Scaphella stearnsii DALL, Proc. Cal. Acad. Sci., 1v, Oct., 1872, p. 270, pl. 1, 
fie £>-ProcaU. SNat.. Mus) xxiv, no. 1264, p. 517, pl xxxv, fig: 4, 
Mar., 1902. 
Shumagin Islands, Alaska, and westward to Captain’s Bay, Una- 
laska, in 40 to 100 fathoms, rocky and muddy bottom; temperature 
of bottom water 37° to 41° Fahr. Also in Bering Sea, northward 
to the line of floating ice in winter, on sandy and muddy bottoms, in 
61 to 350 fathoms; U. S. steamer Albatross. 
U. S. Nat. Mus. (type), 108,993; also 91,352, 108,998, 130,513, 
162,628, 162,629, etc. 
The conchological characteristics of this species are so different 
from those of any of the South American species that one would 
hesitate before including it in the same group without other evidence, 
but an examination of its gross anatomy shows that the general char- 
acteristics of its genitalia and dentition do not differ from those of 
A. magellanica, except in minor details, and consequently the com- 
bination is allowable. Its nearest congener, A. benthalis Dall, in- 
habits the Gulf of Panama at a distance of more than 5000 sea 
miles; and, omitting this abyssal species, the nearest relative occurs 
at a distance of nearly gooo miles. It is probable that “ Voluta” 
Lamberti of the British Crag may be akin to our Alaskan shell. 
Genus ZIDONA H. and A. Adams 
Volutella D’OrpicNy, Voy. Am. Mér., p. 422, 1841; V. angulata SwAINnson, 
sole example, not Volutella Perry, 1811, nor SwAINson, 1830. 
Zidona H. anp A. ApAms, Gen. Rec. Moll., 1, p. 161, 1853; 1, p. 618, 
1858; FiscHer, Man. de Conchyl., p. 605, 1883; CossMANN, Essais 
Pal. Comp., lI, p. 104, 1899. 
The remarkable extension of the mantle and modification of the 
form of the shell are quite sufficient to render this subdivision of 
