2/2 THE COURTSHIP OF ANIMALS 



female. But this being so, how does each discover the 

 condition of the other ? 



Many of the Snails, like Helix nemoralis, are gaily- 

 coloured. Are these hues, these bands of black and 

 yellow, the product of " sexual selection " — the outcome 

 of a process of selection from among the most conspicu- 

 ously coloured individuals as postulated by the Dar- 

 winian theory of Sexual Selection ? If so, then this 

 choice must be regarded as a periodic recurrence 

 coinciding with the period during which the individual 

 is dominated by its female attributes. In due course 

 it becomes, for the time, a male, and may find itself 

 rejected, owing to a lack of intensity in its coloration, 

 or, on the other hand, it may vanquish a rival by its 

 very splendour. Each, in short, would help materially in 

 this process of beautification. If the choice of mating — 

 for it is this rather than a choice of mates — proceeds 

 on these lines, the bright coloration of the members of 

 this species becomes easy to understand. But does it ? 

 It is more than doubtful whether the eyes of Snails are 

 sufficiently good to distinguish the coloration of their 

 neighbours' shells, or for the matter of that of their 

 own, for their eyes being carried on long mobile stalks, 

 they should have no difficulty in contemplating their 

 own charms. And what of Snails of more sober hues ? 

 It seems highly probable that here, as in so many cases, 

 scent is the selecting factor, and the coloration is an 

 " accidental " feature. That the colour of the shell 

 plays no such part as that just postulated may be 

 gathered from the evidence afforded by many marine 

 species, whose shells, though conspicuously marked, are, 

 during life, completely enveloped and concealed by the 

 all-investing, fleshy mantle. In like manner the ex- 



