226 Trof. W. C. M-Iutosh on the 



be said of the purple or orange liue of S. endeca fiom deep 

 water and of CrihreUa sanguinoJenta between tide-marks. 

 The sand-stars (e. g. Ophiura lacertosa) are often tinted of a 

 hue resembling their surroundings, yet they and the more 

 brighlly tinted forms are common in the stomachs of fishes 

 and are eagerly devoured by gulls when stranded on the 

 beach. 



'Jiie common sea-urchins of our own shores are often con- 

 spicuous on the tangles at extreme low water, and their tints 

 nre neither protective nor warning as regards man and certain 

 fishes. Though some species (e. g. Strongylocentrotus lividus) 

 show sexual differences, the male being darker and the female 

 of a violet tint more inclined to red, Sexual Selection need 

 scarcely be considered. The burrowing habit of the species 

 just mentioned would seem to indicate that its colour was 

 neither protective nor warning. The colours and habits of 

 the heart-urchins give the same lessons. Amongst others 

 the green-pea urchin is a favourite food of the haddock. 



'J he brown and purple hues of the sea-cucumbers may in 

 some way subserve protection amongst the dark masses of the 

 tangles, yet both th(y and the transparent forms are found in 

 the stomachs of fishes. In the purple forms in the deep sea 

 Prof. Moseley is of opinion that the colouring is useless, 

 " and is merely due to the persistence of colouring developed 

 originally in shallow-water ancestors." But there may be 

 other explanations which are less theoretical, especially as 

 the same puiple colour is found in a feather-star in shallow 

 water in the tropics and in a sea-cucumber in 1955 fathoms in 

 the antarctic sea. 



The transparent Holothurians and the Synaptidse are often 

 almost colourless, so that the arguments in connexion with 

 coloration do not fit. 



No group is more beautiful or more varied in coloration 

 than the marine Annelids, and no group of Invertebrates 

 offers a better field for the manifestations of protective resem- 

 blance, for the display of warning coloration, and, since the 

 sexes in the majority are separate, for the operations of Sexual 

 Selection. Yet some of the most brilliantly tinted, like the 

 sea-mouse, frequent muddy sand or mud, where the metallic 

 lustre of their resplendent bristles would only betray them; 

 and the same may be said of some of the most conspicuously 

 colouied IJesionidse, e. g. Ojihicdromus. It is true the bright 

 colours and iridescence of many are hidden within tubes, but 

 this would rather point to coloration in these cases being inde- 

 pendent of protection. Even in forms that dwell in sand, 

 like jSeiildhys, Ophelia, and McgelonOj the iridescent pearly 



