2 
beneath it, in front. Scuipture of fine sharp elevateci threads which extend 
from thè vertex to thè margin without bifurcating. These are crossed by very 
fine sharp lines of growth slightly elevated. Lon. 1-03 in., lat. 0'8 in., alt. 
0 33 in. Posterior siepe slightly arched. 
Habitat, Shumagin group of islands, Alaska 'l’erritory, on rocks near low 
water rnark. Dall. 
This lovely species has no relations with A. sijbantica, Dall, and rosacea, 
Cpr., except those of color. The two lattee are mudi smallar and thè rose 
color is much lighter and differently disposed. Its nearest allies are some 
varieties of A. patina, in none of which bave I observed any approach 
to thè color of this species, and which bave a different nucleus, and thè 
scuipture in slender rounded riblets instead of sharp threads. The shell 
of patina is also in generai much more solid and thick. The animai 
partakes of thè rosy ime of thè shell except thè margin of thè mantle 
which is furnished with brown dots. It belongs to thè subgenus CoUi- 
Hcìla. It is worthy of note that when there is a brown marking on thè 
extcrior, in ihe region of thè submarginai internai mottled band, thè latter is 
iuterrupted by a white space corresponding in size and width to thè external 
marking. In spite of thè very great variations in thè species of this genus, I 
feel sufiìciently confident in regard to thè distinetness of this form to describe it 
as a well marked species, excelled in beauty by none. 
Argonauta expansa. Dall, n. s. 
Shell of moderate size, of nearly two involute whorls. Aperture widely ex- 
panded near thè spire, rather narrow in front. Carince rather blunt, furnished 
with about thirty alternate projections, those behind thè posterior edge of thè 
aperture above and below, being tipped with very dark brown. The promi- 
nence of thè projections decreases in thè middle of thè back, and they become 
larger and more prominent toward thè anterior edge of thè aperture. The pro- 
minence of thè luterai radiating folds varies in like manner. Of these about 
twenty-three start from thè axis of thè shell, which is drawn out behind thè 
luterai expansions of thè aperture and supporta them. There are about twenty- 
six intercalary folds. The spire behind thè posterior edge of thè aperture is 
more or less tinged with brown, and there is a livid brownish purple coloration 
on thè luterai extensions of thè axis and that part of thè shell adjacent to them, 
The interior of thè shell is smoothly polished, thè exterior, especially on thè 
protuberances of thè carinm, is covered w’ith a multitude of exceedingly minute 
rough pustules, which give a very rough, harsh feel to thè shell, and under a 
lens appear hemispherical. Laying thè shell upon its aperture, with thè apex 
posterior, we bave thè following measurements. Total length 3,25 in. Width 
of dorsal area posteriorly 0’32 in., do. anteriorly O I.Height of shell 2 0 inches. 
Total extension of axis from end to end, 4 inches. Total length of aperture 
2-25 inches, length from thè anterior edge of thè spire to thè anterior edge of 
thè aperture l'9 inches. 
Habitat, in thè Gulf of California. 
This pretty and peculiar argonaut possesses an assemblage of characters not 
common to any described species, though there are several which bave a some- 
