403 
of Gasteropodous Mollusca. 
coast may be accounted for by the difference of climate^ as their 
position in shallow pools exposes them a good deal to change of 
temperature. The spawn forms a small pear-shaped, transparent, 
gelatinous mass (PL XIX. fig. 7), with the ova, which are yel- 
low, imbedded in the centre. Some spawn, deposited by an in- 
dividual, in a vessel of sea-water, on the 3rd or 4th of June, was 
hatched, and the larvae swimming about on the 20th of the same 
month. The larva very much resembles that of the Nudibranchs, 
as may be seen by a reference to the figure (PI. XIX. fig. 8), 
having, in that state, a transparent shell and an operculum, which 
afterwards disappear. A transparent and nearly colourless va- 
riety of Limapontia nigra is frequently found at Cullercoats, in 
which the green biliary organ is seen through the skin, as repre- 
sented in PL XIX. fig. 5. 
This species, when bruised, has a peculiar sweetish smell, like 
that of moist sugar, which appears to be derived from the Con- 
ferva it feeds upon. 
In Loven^s ^ Index Molluscoriim Scandinavise ^ this species is 
made synonymous with Planaria limacina, O. Pabricius, and P. 
capitata, Muller. The former we can find no description of, but 
the Fasciola capitata of Muller (Verm. 70) may be either this or 
a nearly allied species. He describes it however to be spotted 
with white, which is scarcely a character of L. nigra^. 
Acteonia corrugata, n. s. PL XIX. figs. 2, 3. 
Body limaciform, black, depressed, somewhat bulged at the 
sides, and covered with regular wrinkles like an Avion. On each 
side of the body there is a slightly elevated ridge, with a few pale 
tubercular spots. Head carinated at the sides ; each carina being 
produced above into a short, flat, ear-like tentacular process, 
which is whitish. The eyes are placed in circular palish spots at 
the posterior extremity of the ridges. The posterior extremity 
is obtuse and pale ; there is also a palish spot near the centre of 
the back. Foot linear. Length one-eighth of an inch. 
Found by Mr. Cocks at Falmouth along with the last, and 
feeding upon the same Conferva, but rare. 
The genus Acteonia was formed by M. de Quatrefages for a 
small mollusk found on the French coast. It comes very near to 
the last, the chief difference being in the form of the carinated 
ridges at the sides of the head, which in this are produced into 
flat, blunt, angular projections making an approach towards ten- 
tacles. 
* Perhaps Fasciola capitata may be the black species Pelta, described 
in the ‘ Ann. of Nat. Hist.’ vol. xviii. p. 289, which agrees with Muller’s de- 
scription in having a ridge along the side, and is also sprinkled with pale 
spots. 
27 * 
