24 NEMERTINES OF PLYMOUTH SOUND. 
25. L. tacrgus, Montagu. 
This species seems commoner in the Mediterranean than on the 
Atlantic shores; at least Joubin states that it is commoner at 
Banyuls than at Roscoff, and Birger describes it as “ tolerably 
common ” at Naples, though Hubrecht does not seem to have found 
it there. I have not obtained many specimens. ‘The north side of 
Drake’s Island, between tide-marks, seems the most favorable 
locality, though isolated specimens have also been obtained in 
Cawsand Bay. All the individuals were small, measuring only from 
5 to 10 em. in length, whereas those described by McIntosh were one 
or two feet. Ihave not met with either ripe specimens or eggs. At 
Banyuls they are said to breed towards the end of May. 
26, L. pinrneatus, Renier. 
CEREBRATULUS BILINEATUS, Hubrecht. 
LINEUS BILINEATUS, McIntosh. 
Fairly common in from 5 to 20 fathoms. _ It is especially abundant 
at the Duke Rock among the shells and stones, though numbers of 
individuals have been obtained from the west channel and elsewhere. 
One small specimen was obtained among corallines in tide-pools on the 
east side of Drake’s Island. It is the dark-coloured specimen 
mentioned below. The greater number of the specimens which I 
have seen are small, being only from 3 to 5 cm. long. Only one was 
a fair size. This was dredged at the Duke Rock on May 14th. 
Its length could not be determined, as its tail was missing, but its 
breadth was 0°5 cm., so that its length when complete must have 
been at least 12 to 15 cm. 
This species is very variable in colour. The majority of individuals 
were of a creamy white, inclining to reddishness. In some the 
brown-red pigment granules were localised in patches here and 
there. As the larger specimens almost invariably showed more 
colour than the smaller, I was inclined at first to think that these 
differences indicated merely stages in development. The finding, 
however, of a very small specimen between 2 and 3 cm. long, which 
was of a dark uniform chocolate-brown, seems to poimt rather to 
colour variation as the explanation, and this is strengthened by the 
fact that I have found specimens 4 cm. long perfectly white. The 
colour of the single large specimen was a beautiful dark purple. 
In all the specimens I have seen the dorso-median line is double, 
being divided by a thin line of the same colour as that diffused over 
the body. Those described by Birger from Naples are without the 
median dividing line, though Hubrecht has found there specimens 
