NUDIBRANCHIATA OF THE L.M.B.C. DISTRICT. 133 
as to be a striking object in a white dish or a vessel of 
clear water, it is quite inconspicuous on the dark purple- 
brown rocks spotted with patches of adhering mud, sand, 
small alge and zoophytes found in this neighbourhood. 
We were much impressed with this on a recent visit 
(March, 1890) to Hilbre Island when we found that a reef 
of rock we were exploring had a number of specimens of 
this species scattered over it which were not at first 
noticed because of the perfect manner in which their 
colours blended with those of the surroundings.* 
Lamellidoris proxima, Ald. and Hance. 
We have taken this again at Puffin Island and Hilbre 
Island, and Dr. Hanitsch found it at Port Erin, Isle of 
Man, in April, 1890. 
Acanthodoris pilosa, O. F. Muller. 
Found again at Hilbre Island, March, 1890—colour dark 
erey. Transverse sections of this species bring out very 
clearly that the large papillae on the dorsal surface are 
much more prominent on the sides than along the middle 
line of the back (PI. VI. fig. 5). 
Family PoLycERIDz. 
Goniodoris nodosa, Montagu. 
Found at Port Erin, Isle of Man, in April, 1890, by Dr. 
Hanitsch. We have made use of specimens of this species 
for an enquiry into the condition of the epipodial ridges 
(Pl. VI. fig. 6) which will be discussed below. 
Polycera quadrilineata, O. F. Muller. 
Dr. Hanitsch obtained some specimens at Port Erin, 
Isle of Man, in April, 1890. We have found this species 
an important transition form, in the condition of the 
* In this connection see the experiments on fishes given on p. 152, and the 
remarks on colour on p. 162. 
