86 THE APODID^ PART I 



this very roughness might favour the attachment of 

 spores. 



(2) There are, further, short straight hairs wh'ch 

 seemed to be sensory, but all our attempts to trace 

 their elements through the cuticle were baffled ; in 

 one place alone, where the cuticle was split from the 

 hypodermis, we saw fine processes connecting the 

 points where the hairs arose with the hypodermis, 

 and these may have been nerve fibres. These short 

 hairs are very numerous, especially in the frontal and 

 dorsal regions of the head. 



(3) There are undoubted sensory hairs whose 

 nerves even with a low power are easy to follow into 

 the hypodermis, where they probably join the sub- 

 hypodermal nerve plexus. 



(4) The sensory hairs and setae on the limbs may 

 perhaps be classified as follows. 



(a) Tufts of minute hairs on small papillae round 

 the edges of the endites, and along the outer edges 

 of the gnathobases. 



(/3) Long feathered hairs on the gnathobases, occur- 

 ring together with sharp tooth-like setae, which latter 

 help to give the gnathobases the character of jaws 

 (see Fig. 9, p. 47). The nerves of these highly 

 developed tactile hairs are easy to follow ; the 

 ganglia at their roots are compound (see Fig. 31, 



p. 130- 



(7) A fringe of similarly feathered hairs round the 

 flabella, which we. have homologised with the sensory 

 cirri of the dorsal parapodia. The flabella being 

 transparent, the nerves can easily be followed. 



