CLASS GASTROPODA 
171 
arctissime punctato-striatis minutis, ultimo anfractu in medio usque ad 
basin laeviore, apertura oblonga, labro exteriore recto, intus laevi, cineras- 
cente, columella quadriplicata. Long., 2.25; lat., 75 in. (Melvill.) 
This interesting species belongs to a section of the genus which has its 
headquarters on the western shores of North America and Mexico, and of 
which M. lens Wood may be taken as the type, all the species possessing a 
black or dark brown epidermis, and being more or less decussate or puncto- 
striate, and it is not unlike the recently described M. fultoni E. A. Smith 
from the same locality. Differentiation, however, seems easy between 
them. M. fultoni exhibits a more distinct transverse punctuation, the pit¬ 
ting being both deeper and wider, the whorls are also ventricose, and the 
spire more acuminate, and attenuate in comparison. The outer lip, too, is 
more effuse thin in M. idae. With M. caliginosa Reeve, both species show 
more affinity, but here again, the transverse sulci are more regular, and 
scarcely punctate. I have seen nearly thirty specimens of this new form, 
and a good many also of M. fultoni , all keeping well to their individual 
characteristics. (Melvill.) 
Type in B. J. R. LeB. Tomlin Collection, England. Type locality, Point 
Loma, California. 
Range. Farallon Islands to Cortez Bank, California. 
Mitra idae montereyensis Berry, 1920 
Proceedings of the Malacological Society of London, 14: 31; text figures, 1-4. 
Shell of good size, robust, heavy, spindle-shaped, the maximum width 
contained in the length somewhat less than three times; whorls slightly 
convex on the spire, the latter tapering quite rapidly; sutures distinct but 
only weakly indented. Aperture ample, its extreme measurement nearly or 
quite one-half the entire length of the shell; the heavy outer lip suffers 
moderate thinning at the edge; columellar plaits strong and primarily 
three, but there is apt to be an incipient fourth one where the columella 
begins to draw into the canal in front, and a small adventitious plait now 
and then appears between two of the major ones. Canal short, weakly up¬ 
turned. Practically the entire shell sculptured by numerous, rather fine, 
spiral threads, sometimes more or less obsolete on the peripheral region, 
and frequently so cut by the lines of growth as to result in an appearance 
of minute pitting, the spiral threads heaviest and coarsest in the region of 
the canal and the front of the shell generally. Lines of growth and in¬ 
cremental ridges numerous, varying from fine to coarse and irregular. 
Entire shell covered by a strong black or very dark brown periostracum. 
Interior of the shell white, or brownish-white, the columellar region (ex- 
f 171 1 
