Coloration oj Murine Auimals. 21^3 



specially deliglits in tlu; diirk surfaces of stones in rock-pools 

 Iron) l()\\-\vattT mark to sonic distance above lialt-ti<le ? The 

 unpractiscil eye would ccrtaiidy mistake these rou;^h little 

 lumps for muddy and stunted masses of zoophytes and debris. 

 How are their pjem-like dots of pip;ment to he explained? 

 Karely ^Ef/inis has been found crawliiii^ just under thewaler- 

 line in a sequestered pool. Polycera quadn'lineuta, P. ocellnta^ 

 and Ancula cristaUi wW occur under stones in quiet rock-|)Ool-5, 

 and are not difficult to detect in their habitats. It is doubtful 

 if they are in want of protective or warning coloration in such 

 places, especially when it is found that in these localities 

 Doto coronata, which swarms on the branches of Sertularia 

 puniila, requires careful and minute inspection to detect it. 

 it is pale and devoid of much of the beauty of the dee|>- 

 water specimens so often tossed on shore on the blades of the 

 tangles covered by forests of Ohelia geniculata or on Hydnill- 

 »na/jta /a ^ca/a brought in by the fishing-boats. A clearer case 

 of harmony with environment, however, is that of Trilonia 

 pleieia on Alci/onhtm, yet it is readily seen when frequenting 

 Ohelia genicitluta on the blades of tangles. 



Un the other hand, the dog-whelk between tide-marks is 

 fairly conspicuous, and so is the cowry, especially when the 

 soft parts are protruded. The colours of the Eoiids are 

 remarkably bright, and cannot therefore be protective in so 

 far as being in harmony with their surroundings. It has 

 yet to be proved that they are warning colours, for it nceils a 

 considerable amount of inedibility to scare a hungry fish, and 

 the cod docs not respect this property (if it exists) in Eolis 

 papulosa. Fishes which are partial to anemones might be 

 supposed to be careless of the nematocysts of Nudibrauchs. 

 Further, the haunts of the Eolides and an attentive survey 

 of their coloration leads to no conclusive results. The 

 amethystine a>id ultramarine hues of E. coronata and the 

 scarlet or bright biick-red of E. rujibranchialis seem to have 

 no relation to their surroundings, and does not prevent their 

 being devoured by their hungry fellows when disabled or 

 dead. Tiie same may be said of the fine purplish and the 

 orange varieties of Eolis Farrani and of E. Adelaides. The 

 SMJaller Eulis olivacea and E. viridis are not so easily seen on 

 the under surfaces of the stones they frequent ; but immersion 

 of these in sea-water readily shows them. 



Prof, llerdman, who has given much attention to the 

 colours of Nudibranchs, truly considers that " the red-brown " 

 hues of Dendronotus cfTectively conceal it. Some, however, 

 are brightly tinted with scarlet and rose-pink, ainl a splendid 

 wiiite Viiriety is couimon in the same haunts in deep water 



