542 
A. E. Verrill — Catalogue of Marine Molhusea. 
face of the mantle, over the left side of the neck, and extending ob- 
liquely across and over the neck to the right side. 
The largest specimens are badly broken; some of them were about 
10 'nm j n length; greatest diameter of operculum, 6 ,um ; breadth 4’5 mm . 
A perfect but small specimen is 6 mul long ; breadth, 6 u,m ; length of 
body- whorl, 5 •2 mm ; length of aperture, 4 mm ; its breadth, 3 •2 m,, l. 
Station 1031, off Martha’s Vineyard, in 255 fathoms, 1881. About 
a dozen specimens, all living, were taken from the interior of an old 
egg-case of a skate ( Eaia , sp.). Most of them were badly broken. 
I have compared these specimens directly with original specimens 
of the fossil Choristes elegans , found in the post-pliocene of Canada 
by Principal J. W. Dawson, who very kindly sent me specimens, 
both adult and young, for examination. I have figured a young 
fossil specimen for convenient comparison (pi. LVIII, fig. 28.) 
Our specimens agree very closely Avitli the smaller fossil ones, in 
form and structure. The principal difference is in the much thinner 
and more fragile texture of the recent shells. This may be due to 
mere local conditions. Therefore, until more specimens of the recent 
shell are obtained, I prefer to consider it a thin and delicate variety 
of the ancient type. 
Cylichna Dalli Verrill, sp. nov. (Ctenus provisional). 
Shell elongated, white, translucent, somewhat barrel-shaped, a little 
broader medially, but nearer the anterior end; considerably narrowed 
posteriorly, with a small pit at the apex. No umbilicus. Aperture 
as long as the shell, \ r ery much narrowed posteriorly, and ending in 
a narrow slit in the sutural line ; anteriorly it increases gradually 
about to the anterior third, when it suddenly expands into an ovate 
anterior portion, by the strong excurvature of the columella-margin, 
and a slight expansion of the outer lip. The outer lip rises, posterior- 
ly, slightly above the level of the body-Avhorl, in the form of a thin 
edge, separated from the body-whorl by a narrow, deep fissure; pass- 
ing backward it forms a gently sloping shoulder, and is \ r ery slightly 
convex and divergent to the anterior end, A\diere it is cut aAvay for 
the entire width of the shell, and joins the colmnella-lip in a regu- 
lar curve, with a sharp edge, not reflexed ; the columella-margin 
is strongly excavated and sinuous, and in the larger specimen has a 
slight fold, anteriorly; a thin, white callus covers the inner lip. 
The body-whorl is broadly convex, rounded off gently anteriorly, 
and more abruptly posteriorly. The pit, at the apex, is well de- 
fined, showing some of the volutions, but is injured in both of my 
