10 NEMERTINES OF PLYMOUTH SOUND. 
Order 3.—_METANEMERTINI, Biirger. 
The lateral nerves have completely broken through the muscular 
coat of the body-wall, and have come to lie within it in the paren- 
chyma. The body-wall consists of epidermis, a circular muscular 
layer, and a longitudinal muscular layer. The mouth is situated in 
front of the brain. The proboscis, with few exceptions, is provided 
with a stylet. 
Family AMPHIPORIDAN, Hubrecht. 
Genus AMPHIPORUS, Ehrenberg. 
7. A. tactreLorEus, McIntosh. 
Nearly as common as J. obscurus. Lives between tide-marks 
under stones. The arrangement of the eyes in two groups on each 
side, the posterior group generally forming a triangle, with one eye- 
speck (that most remote from the snout) much larger than the rest, 
is very characteristic. 
The colour is very variable ; many shades of white and whitish 
pink are represented, but the commonest colour is perhaps light 
brown. I have never met with a green variety, though this seems 
common on the French coast, and has been found at Guernsey. 
Ripe specimens and eggs were found in the early spring. 
8. A. DISSIMULANS, N. sp. 
I have established this species for a very abundant Amphiporus 
which I at first took to be Amphiporus pulcher. It agreed with this 
species in the general shape of the body, with its oar-like tail; in 
the broadly spathulate pointed head, so different in appearance from 
that of A. lactifloreus, and, in contrast to the latter, sharply separated 
from the body; in the arrangement of the eyes, which are never 
divided into groups ; and in habitat occurring only in from 15 to 20 
fathoms. 
The average length is 5em.; the colour is variable, but most 
frequently is a very pale pink, the pink being rather pronounced 
anteriorly, but posteriorly passing into a bluish tint. The tip of the 
snout has a central papilla, from which an opaque line passes back a 
short distance. The eyes are very numerous; in one specimen I 
counted forty onone side. The brain can be seen as a red object shin- 
ing through the skin, but it is not so conspicuous as in A, /actifloreus. 
