I have not been able to compare these species with those from South America described by D’Orbigny and others; but, like our other littoral mollusca, they are probably distinct. I have, however, found the pelagic species Ommastrephes giganteus D’Orb in large numbers, and “hundreds” of a species of Argonauta washed ashore last spring as far north as Santa Cruz Island, as I was informed by Dr. Shaw, who presented specimens to the State collection.
Aplysia Linn.
A. californica Cooper. State Collection, species 1045.
Form and external appearance as usual in the genus. Length fifteen inches, breadth five, height about the same. Color pale gray or greenish, becoming purplish on the side, folds of mantle with scattered white specks, from which an irregular network of brown lines extends over the rest of the body, interspersed with large brown blotches. Inner surface of mantle varied with alternating painted bars of white and dark brown interlocking together. Sole of foot black. Eyes very minute and black.
Shell contained in the substance of the mantle cartilaginous, translucent, trapezoidal or hatchet-shaped, margins rounded, slightly convex above, the nucleus or centre in old specimens distant from the posterior end or apex. Faint radiating lines diverging from the nucleus, crossed by an irregular network of darker lines, all ending abruptly at some distance from the margin, which has thus a wide, nearly transparent border. An accessory plate arises on the inner surface from the nucleus, spatulate in form and slightly raised.
The two younger specimens have the clear border and accessory plate less developed, and very young ones do not probably show these characters at all, but resemble the typical Aplysia in the form of the shell. On this account I am unwilling to constitute it a new genus, but propose to call it a sub-genus under the name of Neaplysia.
There was no appearance of a multiplication of shells, said to occur in old specimens of Aplysia. Not having any full description of the internal anatomy of Aplysia, I cannot at present determine whether there are many other differences in structure.
The stomach was full of large fragments of Algæ. I found three specimens only, on the beach at San Pedro, July 25th, just after a heavy blow which occurred at the lowest summer tides. Kept in water for some time, they were very slow and uninteresting in movements, showing no evidence of any means of defence except the exudation of a beautiful purple fluid from the mantle when handled. This fluid, common to the Aplysiæ, though formerly supposed to be poisonous and indelible, possesses no such properties, though it may be a defence against marine animals which attack them.
The figure, taken from a tracing of the shell, and electrotyped by Dr. A. Kellogg, represent the inner surface of the most developed specimen, of the natural size.
