100 MARINE BIOLOGY OF THE SUDANESE RED SEA. 
TREVELYANA STRIATA, Sp. nov. 
The notes on the living animal are as follows :— 
“ From shallow water: bottom mud and weed. 3:7 cm. long, white with 
thick definite bands of bright dark yellow. One forms a border to the 
mantle and foot, others, which are broken, extend down the back and sides of 
the body. All are raised more or less. Gills as in Trevelyana, pinnee more 
or less parallel with the rhachis. In this species the gills are arranged in a 
transverse row across the body and project on either side. The middle three 
in front of the anus are reduced: the whole are placed at about the middle 
of the length of the body. The rhinophores and rhachis of gills are also 
yellow. Tail short and blunt ; the median yellow line upon it is much raised 
into a crest. The animal is very soft and contractile.” 
As preserved it is much contracted and the external features are distorted : 
but as Mr. Crossland labelled it Trevelyana it probably had the usual shape 
of that genus when alive. The ridges are still plain and the following can 
be distinguished :—(a) a medio-dorsal ridge, well-developed behind the 
branchiz but imperfect in front of them ; ()) a ridge on either side of this, 
well-developed before the branchize but imperfect behind them ; (c) a ridge 
running completely round the body and forming, as far as can be judged. 
both a mantle-border and a frontal veil ; (d) two ridges on the sides of the 
body. All these ridges are very distinct and about one millimetre high. 
The anterior part of the body is much retracted, aud the rhinophore 
openings cannot be seen. The branchive form a straight transverse line in a 
cleft. In the middle are three small ones in front of the others. Those at 
the sides are larger and pectinate, but it is difficult to count the number as 
smaller plumes are mixed with the large ones, and might be variously 
considered as separate or annexes. There are about 6 large plumes on either 
side of the centre. 
The blood-gland is thick and purplish grey. The central nervous system 
consists of three very distinct pairs of ganglia, the cerebral and pleural 
ganglia being clearly distinguished. The salivary glands consist of two 
short, thick, white bands. No trace of an armature was found on the labial 
cuticle. The radula is fragile and torn into two pieces. The formula is 
apparently about 14x 18.0.18; but perhaps there are as many as 22 teeth 
in some rows. The teeth are awl-shaped and all much the same ; but those 
which appear to be the innermost (though their position is not quite certain) 
are taller and straighter than the rest and have smaller bases. 
The hermaphrodite gland is represented by a single irregularly shaped 
mass, which is deeply furrowed but not divided into separate globules. The 
spermatotheca is small and round: the spermatocyst of about the same size 
and pear-shaped. The penis and the lower portion of the small vas deferens 
are armed with minute transparent spines. A reticulate gland, resembling the 
