SIR C. ELIOT—REPORT ON THE NUDIBRANCHS. 101 
prostate of Huplocamus but smaller, envelops the vas deferens, the sper- 
matocyst, and the spermatotheca. 
This animal does not coincide with any of the recorded species of Tvevel- 
yana. Externally it is characterized by the very distinct and prominent 
ridges ; in the internal genitalia, the hermaphrodite gland and the prostate 
offer peculiarities. 
OHoLA PACIFICA, Bergh. 
(Bergh: ‘Challenger’ Expedition, Zool. x. Nudibranchiata, p. 52, 1884.) 
The notes on the living animal say: “ Polycerid from Mersa Makdah, 
7 fathoms. Of an extremely soft gelatinous consistency and bright orange 
colour except for certain marks of black and dark blue, e.g., the edges of 
the rhinophore cups are black, the rhinophores themselves blue: the gills 
have each a black line on the back of the rhachis ; there are marks on the 
processes behind the gills, on the tip of the tail and at the angles of the 
velum.” 
The preserved specimen is 17 mm. long, 6 mm. broad, and 7:5 mm. high 
without counting the gills. The free part of the tail is 4 mm. long. The 
animal is stoutly built, and the colour, which has now become grey and 
black, is distributed as described above. The head parts are contracted and 
distorted, so that the structure of the rhinophore sheaths is not very plain. 
It would appear that the openings are partly surrounded by a fold of skin, 
and protected on the outside by a large process about 2 mm. long. The 
rhinophores are small, dark, deeply retracted, and bear a few perfoliations. 
The branchiz are four or five. In front of the anal papilla is a very large 
and strong plume, with an accessory plume on the left. The lateral plumes 
on either hand are also strong and distinct but not so tall. Behind the anal 
papilla are some small low branchial tufts which are not combined into a 
plume. Behind the branchiz are two large processes 4 mm. long, and on the 
tail what looks like the remains of a Jagged crest. 
The central nervous system, as seen from above, shows four very distinct 
divisions arranged in a line on the cesophagus. The pedal ganglia are 
roundish: the cerebral and pleural ganglia are fused into an elliptical or 
pear-shaped mass, but the two parts can be distinguished. 
The jaws are yellow with processes attached as in Polycera quadrilineata. 
The radula consists of 12 well-formed rows and two more in a shadowy and 
undeveloped condition. The formula of the rows is 2+2.0.2+2. There 
is no central tooth, and the rhachis is broad. The two innermost teeth are 
hamate much as in Polycera, and dark brown. ‘Then come two plate-like 
teeth, one rather large, the other very small, and both colourless. 
The lower part of the vas deferens is thickly armed with spines bent at 
various angles. 
