134 LIVERPOOL BIOLOGICAL SOCIETY. 



dorsal ridges and epipodial processes, between Goniodoris 

 and AncidaA The anterior part of the body in the 

 region of the rhinophore shows in transverse section 

 (PI. YI. fig. 7, e.p.) a prominent lateral ridge which becomes 

 considerably lower as it is traced back (PI. VI. fig. 8, 

 right side) , and then rises again at the sides of the bran- 

 chiae (PI. VI. fig. 8, left side, and fig. 9) and immediately 

 behind them to form prominent cerata comparable with 

 those of Ancula (PI. VI. fig. 10). These posteriorly placed 

 cerata of Polycera contain numerous large glands (PI. VII. 

 figs. 3 and 4) which we shall have to refer to again in 

 connection with Ancula (p. 136). 



Ancula cristata, Alder. 



This species was found by Dr. Hanitsch at Port Erin, 

 in April, 1890, and we took it in extraordinary profusion 

 at Hilbre Island in March, 1890. On one reef of rocks 

 especially, a little way above low water mark, there must 

 have been many thousands of specimens present. For 

 yards it was impossible to walk without treading on them 

 and handfuls were readily collected by scraping the speci- 

 mens together from the mud-covered rocks. Many of these 

 were kept alive and used for the experiments with fishes at 

 the Aquarium described below. 



The variation in size and colouring of this species at 

 Hilbre is very great, and the larger specimens are almost 

 invariably white, light grey or almost colourless, while the 

 smaller ones are more or less conspicuously ornamented 

 with bright yellow. This species is very slimy, and a num- 

 ber of specimens put together in a bottle very soon form a 



tGarstaiig (loc. cit. p. 181) has already pointed out that the cerata of an 

 allied forni, Iiiaha aspersa, are plainly homologous with the ridges of 

 Goniodoris &c., and the epipodial folds of Doris; and has expressed his 

 belief that their honiologues are to be found in Tritonia, Lomanotus and 

 Eulis. See also, Herdman, Quart. Journ. Micr. Sci., vol. xxxi., p. 42, 



