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PKOCEEDINGS OF THE I!TATIONAL. MUSEUM 



VOL. 80 



In the fifteenth parapodium the dorsal and ventral cirri are 

 relatively much smaller and more slender, and the parapodial lobe 

 is heavy and blunt pointed. (Fig. 1, c.) The dorsal lobe is now 

 double and the seta tuft arises between the two parts. A single 

 large acicula occurs in each part of the parapodium. In parapodia 

 from the posterior part of the body the dorsal half of the upper 

 parapodial lobe is, relatively to the others, much larger and bears 

 the slender dorsal cirrus near its apex. The ventral cirrus is small 

 and inconspicuous. (Fig. 1, d.) In the first parajDodium the setae 



Figure 1. — Nereis heterocirrata, new species : o. Head, X 7.5 ; h, first 

 parapodium, X 18 ; c, flf teentli parapodium, X 36 ; d, posterior 

 parapodium, X 27.5 ; e, seta from first parapodium, X 250 



on the ventral part of the seta tuft have short terminal joints that 

 carry long, heavy spines on the inner margins (fig. 1, e) ; those of 

 the dorsal tuft have long and slender terminal joints, and these are 

 finely toothed along one margin. In the posterior portions of the 

 body the seta are badly broken, but so far as it is possible to tell 

 both of the above varieties occur there. In addition are some with 

 much more slender, noticeably " camerated " shafts, the terminal 

 joints flat, elongated triangular in outline, with prominent marginal 

 spines. 



Type.—U.S.l!iM. No. 19323. 



