402 Messrs. Alder and Hancock on a proposed New Order 
Limapontia nigra, Johnston. PL XIX. figs. 4, 5, 6 . JoLnst. 
in Loud. Mag. Nat. Hist. vol. ix. p. 79. 
Body black, or sometimes of a transparent brownish green, 
rather depressed, the sides slightly overhanging the foot. When 
in full progression the sides are almost parallel, but more fre- 
quently they are a little convex, and when the animal is at rest 
it becomes nearly circular. Head truncated in front and flat at 
the sides, where it is elevated into two crest-like ridges, arched 
from behind forwards. Eyes large, situated at the posterior ex- 
tremity of the crests, in a pale circular space, which is prolonged 
on the crest. Foot of a yellowish colour, slightly stained by the 
viscera ; narrower than the body ; the sides are parallel, and it 
tapers gradually to a bluntish point behind ; in front it is trun- 
cated with the angles rounded. Length line. 
A single specimen was obtained by Dr. Johnston in Berwick 
Bay ; since which it has been found in great abundance by 
Mr. Cocks at Falmouth, in small pools among the rocks, between 
half-tide and high-water marks, feeding upon Conferva glances- 
cens. We have also got it in similar situations at Cullercoats, 
and Mr. Richard Howse has taken it at Whitburn. 
The following observations on this species have been commu- 
nicated to us by Mr. Cocks : — “ They are found on Conferva glau- 
cescens; they eat its branches and the microscopic larvae with 
which the plant is infested. In July 1847 I procured a portion 
of the Conferva, not more than one inch in length and four- 
eighths in breadth, containing upwards of twenty patches of 
spawn ; each patch contained from 50 to 150 ova. Stragglers 
are sometimes met with on the Conferva albida ; but the spawn, 
never. I have found them in the shallow pools on the rocks at 
half-tide in the months of April, May, June, July, August, Sep- 
tember, October, and November. In December I visited all my 
old haunts, but without success : the slugs had migrated, and the 
Conferva was in a decayed state or dead. In fine warm weather 
they congregate on the surface of the Conferva, but in dull, cold, 
or windy weather, they descend towards the lower portion of the 
plant. They are active, very hardy, and tenacious of life. I 
have kept them in bottles for a month or six weeks, without 
changing the water, with apparently very little injury. 
They appear to be most plentiful during the months of June 
and July, at which time we met with them in great abundance at 
Cullercoats ; but on visiting the same spot again in the autumn, 
not a single individual was to be found. It is probable that the 
old individuals die off during the winter, and the young brood 
do not come to maturity until the following year. Their remain- 
ing so much longer on the Cornish than on the Northumberland 
