OtlSTHOBKANCHIATA FROM THE ABEOLHOS ISLANDS. 555 
SO that on the outside it obliterates the bine band and on the inside it passes 
across to the other side as a broad band, thus isolating, as it were, two islands 
oE the light blue ground-colour on the notseum. Two similar bands of dark 
colour pass back on the dorsal surface of the tail. 
In the preserved specimens all trace of the orange^ red, and bright blae 
colours has disappeared and the whole ground-colour is of a dirty brownish 
fawn ; the dark lines, on the other hand, are quite clearly visible. In addition 
to those already noted on the drawing, a narrow dark band passes around 
the sides of the body at the line of junction of the mantle-fold, and near the 
anterior end it loo[is downwards and backwards. It then passes back 
parallel with its former course, but lower down the side of the body, as a 
fairly broad streak running out on the dorsal surface of the tail as the two 
lines already noLed. Under the posterior end of the mantle all these dark 
lines may unite and pass back right to the end of the tail as a single broad 
band. A narrow dark band runs right around the upper margin of the foot 
and out to the tip of the tail, where it may or may not unite with the lines 
already described. 
The striking and characteristic distribution of these dark lines is fairly 
constant in all the specimens and shows well after preservation. 
Dimensions. The specimens were all about the same size, and measured 
when preserved : — notseum 20 mm. long by 10 mm. wide ; foot 22 mm. 
long ; body 17'5 mm. wide. 
Head. The head is quite small and overhung by the forward extension of 
the mantle. The mouth is a small longitudinal slit, and on each side there 
is a small cylindrical tentacle, much contracted in all specimens. 
Foot. The foot is linear and its sides almost parallel. It is rounded and 
bilabiate in front and passes off to a pointed tail posteriorly. The sides of 
the foot are marked off from the body by a marginal flange. Judging from 
the sketch of the living animal, the tail may project beyond the notseum 
about half the length of the latter, but in the preserved specimens it is 
usually curled up and hardly projects at all. 
Rhinojyhores. The rhinophores have a short stalk and a cylindrico-conical 
perfoliate clavirs. They are completely retractile within cavities which have 
a slightly raised margin. 
Branchice. The branchiae are fairly simple and arranged in an almost 
complete circle. The anterior ones are simply pinnate thread-like plumes, 
sometimes tending to be bifid at the distal extremity ; these number nine, 
although there is a tendency to fusion at their bases. At the posterior end 
on each side is a group of four similar, but smaller, plumes more closely 
united at the base, and these when extended may appear as four branches 
from one stalk. 
The anus lies in the middle of the branchial circle. All can be completely 
retracted within a pocket with a circular aperture surrounded by a slightly 
raised margin. 
