294 POLYCHAETA chai 



say but little. Protective resemblance there is undoul >tedly amongst 

 the Polynoids, for the scales of these forms resemble more or 

 less closely the stones or sand amongst which they live ; in the 

 same species there is great variety in coloration. This protective 

 habit is carried still further in the case of Psammolyce by the 

 attachment of sand grains to little cups on the elytra, so that 

 the back of the animal is concealed. Certain commensals, such as 

 Polynoe arenicolae, P. pentactes, are coloured so as to resemble their 

 associates. In a few cases it is possible that the gills of Sabelli- 

 formia are protectively coloured ; for in Sabella pavonia they vary 

 from a light yellowish tint to a deep violet-brown, and the dark 

 markings on them are therefore more or less distinct. Spread 

 out as the gills are in life, they are in many cases difficult to 

 recognise ; it is rather their movement as they are withdrawn 

 that attracts one's attention to them, as the tubes of these 

 worms frequently serve for the attachment of brownish seaweeds, 

 to which the gills bear resemblance. But, as a matter of fact, 

 little work has been done in this direction, and speculation on 

 the matter without evidence is worthless. Many pelagic forms, 

 being transparent, such as Tomopteris and Alciopids, are no doubt 

 protected by their lack of colour ; yet these forms present 

 brightly -coloured spots, the light - producing organs in the 

 parapodia of the former, and the large dark eyes of the latter. 



Semper 1 mentions a case of possible mimicry in a species of 

 Myxicola which lives in the clefts of a coral, Cladocora. The 

 branchial funnel, when expanded, resembles very closely the 

 expanded coral in size, colour, etc. ; but he points out that the 

 species occurs in other situations, where its colouring is not pro- 

 tective. Probably the " mimicry " is in other instances merely 

 accidental. 



No doubt many Polychaetes may be " warningly coloured," but 

 experimental evidence is incomplete. Polycirrus aurantiacus is 

 bright red, with orange tentacles ; these worms were rejected by 

 certain fish. 2 The animal has given up living in tubes as all its 

 allies do, and it is the tentacles which appear to be distasteful 

 to its enemies, for when irritated it coils itself up and wraps 



1 Semper, Animal Life, " Internat. Sci. Series," 1881, p. 401. 



2 The experiments were made by Mr. Garstang at the Laboratory of the Marine 

 Biological Association, and are recorded by Ponlton in The Colours of Animals, 

 "Internat. Sci. Series," 1890, p. 201. 





