POLYNOE SQUAMATA. 



201 



so much the larger, that the notopodium appears like a mere 

 tubercle projecting from its upper surface. In other A7i7ie- 

 lida, however, and in the young state of Polynoe, the notopo- 



_t<^v3 



Fig. 51.—Pol!jnde squamata. 



A. Viewed from above and enlar<2:ed : a. ft, c, etc., as in Fiff. 53, B\ e., elytra; /, space 

 left between tlie two posterior elytra ; g, setae and fimbriae of the elytra. 



B. Posterior extremity, inferior view: c?, i)ygidial cirri; h, inferior tubercle; c, c', 

 notopodial and neiiropodial cirri. 



C. Secticm of lialf a somite with elytron : i, notopodium ; 1% neuropodium. 



D. Section of half a somite with cirrus. 



dium is as large as the neuropodium. Both divisions of the 

 parapodia are armed with peculiar stiff, hair-like appendages 

 (//), composed of cliitin, and developed within diverticula of 

 the intcgment, or trichophores^ in which tlieir bases always 

 remain inclosed. These can be protruded and retracted by 

 muscles attached to their sacs, and they vary exceedingly in 

 form. Three distinct kinds are observable in Pohpide alone. 

 The notopodium and the neuropodium carry each a single, 

 sharp, style-like aciculum^ the greater part of the length of 

 which is imbedded in the parapodium and its divisions, while 

 the point just projects at about the centre of the latter. The 

 neuropodial is very much longer than the notopodial aciculum. 



