NEMERTINES OF PLYMOUTH SOUND. 9 
varying from 10 to 15 cm. in length. A few individuals have been 
obtained by dredging in the deeper water outside the Breakwater, 
but the bulk of my specimens have been obtained in the sand 
between tide-marks at Rum Bay. They have not yet been found in 
a sunilar situation in any other locality. Joubin states that his 
specimens came from black muddy sand, and he contrasts this 
species with C. bioculata in this respect, as, according to him, the 
latter lives in pure yellow sand. This difference of habitat in the 
case of the two species does not appear to hold good for Plymouth 
forms. Here both species are found in clean coarse sand, and I 
have occasionally found C. bioculata in black mud. 
6. C. BlocuLATA, Oersted. 
This common species may be obtained almost everywhere between 
tide-marks. As I have already said, a few specimens have been 
occasionally found in black mud, but the majority in clean, coarse 
sand. Large numbers live among corallines, and may be captured 
by collecting the latter. Unless Birger’s C. hymenzus is a variety 
of this species, it does not occur at Naples, but the difference 
between them is very slight, consisting as regards C. hymeneus in a 
reduction of the red pigment on the head to the two red specks, and 
the presence of grains of blue pigment in the latter. A difference of 
habitat is also mentioned, C. hymenzus never being found in sand, 
but associated with Tetrastemma coronatum. At Plymouth Tetra- 
stemma coronatumis abundant among the corallines in tide-pools, where 
it is associated with the present species. 
The breeding period lasts from early spring until the beginning of 
autumn. Ripe specimens were first found in April, and none were 
found later than August. As I have already mentioned, pelagic larvee 
were obtained from the tow-net as late as December. The largest of 
these was 3 mm. long, and was provided with an additional pair of 
marginal lappets, situated between the pair figured by McIntosh and 
Barrois and the anterior extremity. The eyes were situated at the 
margin of the head, and relatively far back. Some days after the 
capture of this larva it gave up pelagic life, and sank to the bottom 
of the vessel. About this time the eyes began to atrophy, and very 
shortly the adult appearance was reached. I have succeeded in 
getting this species to breed in captivity, and hope soon to publish an 
account of its development. 
