POLYNOE SQUAMATA. 



201 



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

 tubercle projecting from its upper surface. Tn other Anne- 

 lida, however, and in the young state of JPoli/noe, the notopo- 



Fig. 51.— Poly tide squamata. 



A. Viewed from above and enlarged : a, b, c, etc., as in Fig. 53, B ; e, elytra ; /, space 



left between the two posterior elytra ; «7, setae and fimbriae of the elytra. 

 J5. Posterior extremity, inferior view : d, pygidial cirri ; A, interior tubercle ; c, c', 



notopodial and neuropodial cirri. 



C. Section of half a somite with elytron : i, notopodium ; k, neuropodiuni. 



D. Section of half a somite with cirrus. 



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

 parapodia are armed with peculiar stiff, hair-like appendages 

 (g), composed of chitin, and developed within diverticula of 

 the integment, or trichophores, in which their 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 Polynoe 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. 



