16 NEMERTINES OF PLYMOUTH SOUND. 
compact and round, were broken up into two little masses of minute 
specks, invisible except under the microscope. Immediately above 
these disintegrated eyes on each side was a shght aggregation of 
orange pigment granules which passed back towards the posterior 
pair, but ended just in front of the anterior grooves. In this and 
the following species there is a tendency towards the formation of a 
median dorsal white line, passing from the snout to the posterior 
extremity. In this specimen the white line was conspicuous, though 
somewhat interrupted in its course posteriorly, and on the snout it 
was continuous with an oval patch of the same white pigment. 
In the slight development of pigment between the anterior and 
posterior eyes, the specimen just described exhibited a character 
which reappeared in another obtained from weeds collected at 
Redding Point. In this specimen, which was of a green colour and 
much resembled the type form, the anterior eyes were normal, and 
close behind them on each side was a little patch of orange pigment 
which, as in the last case, passed backwards towards the posterior eyes, 
becoming imperceptible behind the anterior grooves. A thin median 
dorsal white line passed backward from the snout, but came to an 
end just behind the posterior eyes... The shape of the head of this 
specimen, and the distinctness of the eyes, as well as the structure 
of the stylet region of the proboscis, clearly indicated that it belonged 
to this species. In this development of pigment between the 
anterior and posterior eyes, however, there is the suggestion of a 
transition to 7’. vermiculatum. This suggestion gathers force with 
the finding of varieties in which the characteristics of 7’. vermiculatum 
become more pronounced, and those of the present species less 
marked, until it becomes difficult to determine whether a given 
specimen shall be considered a variety of this or that species. One 
such specimen was obtained on the 21st November ; it was 1 cm. long, 
and in colour resembled the yellow variety of this species; the 
anterior eyes were round and distinct ; the posterior, though equally 
distinct, were much smaller and closer together; the anterior and 
posterior eyes of each side were connected by a band of bright 
orange pigment; the cephalic grooves were not so distinct as they 
usually are in this species, and the head was not so rounded. In this 
particular specimen the proboscis stylet resembled neither that of 
this nor any other species in particular; but in another, which 
exhibited all the above-mentioned characters, the stylet was hke that 
of T. vermiculatum, the handle being much swollen at its base. 
A still nearer approximation to T. vermiculatum was reached by 
an individual dredged from Millbay Channel on the 25th of 
November, which should perhaps be regarded as a variety of that 
species. This specimen, a ripe male 15 mm. long, was of a brighter 
