134 THE NAUTILUS. 
as we know pass Point Concepcion. Many other examples might 
be noted. 
This is not the place to enter into a discussion of the West Coast 
marine faunal provinces. but it is interesting to note that as far as 
the material at hand gives evidence, the two West Coast species of 
Nuttallina are sharply divided by this natural boundary. At Carpin- 
teria, ten miles east of Santa Barbara and at points west of that town, 
to Santa Anita, within ten miles of Point Concepcion, the specimens 
are uniformly V. scabra, as are also the more southernexa mples of 
the genus. Specimens collected at Point Sal, thirty-five miles north- 
ward from Point Concepcion, together with those collected at San 
Simeon, at Monterey, at Purissima and at points near San Fran- 
cisco are uniformly N. californica. No intregrading forms were 
observed. While the external appearance is not always a sure 
guide to specific position, disarticulation of the plates has, in all 
cases examined, revealed the species with certainty. 
A study of numerous specimens from the localities mentioned, 
shows the following differential characteristics, in addition to those 
cited by Mr. Pilsbry. Whether they would hold good in specimens 
from other localities or not, I do not know. In color NV. scabra is 
externally more varied than WN. californica. Specimens of the former 
from Santa Barbara are clouded and mottled with greenish upon a 
buff ground-tint, on the second, third, fifth and sixth valves. The 
remaining valves are much darker and less variegated. In single 
valves of scabra, viewed from above, the broad curving outline of 
the tezmentum on each side is bordered by a small spot of brown, 
placed centrally on the light blue surface of the sutural plates. This 
feature is constant in all of the specimens examined. In UN. cali- 
fornica the spots are wholly absent, or in some cases replaced by in- 
distinct clouds of a color darker than the surface of the sutural 
plates. Of course no one would separate the species because of these 
slight color differences, but taken in conjunction with the weightier 
points of difference furnished by the shape of the plates, sculpture 
and character of the girdle, they are interesting as showing how far 
these geographical races have become ditferentiated from the parent 
stock. 
