238 THE ANNELIDA POLYCHAETA. 



Somite II apodous as usual, coalesced with I at the sides. Nuchal cirri more 

 slender than tentacles, like which they are smooth, subulate, reaching to near 

 middle of prostomium. 



The succeeding somites bearing parapodia, regular, undivided; at widest 

 part of body about seven to eight times as wide as long, posteriorly only four to 

 five times wider than long. Strongly arched above, ventrally slightly arched, 

 with deep median longitudinal neural groove. The greatest width is attained 

 in the region of somite XXV, from whence the body width is nearly uniform to 

 near somite XL, following which it gradually decreases. 



Parapodia simple rounded processes of the form and arrangement usual in 

 the genus. Notocirri conspicuous, proximally stout, distally strongly tapered, 

 subulate; posteriorly more slender, as usual. Neurocirri anteriorly with large, 

 conspicuously swollen, bases of elliptic outline on each of which is borne a 

 very short, abruptly greatly thinner style; posteriorly the base is less swollen 

 and finally passes gradually into the style, the whole cirrus being somewhat 

 subcorneal; short, but little exceeding the parapodium. 



Branchiae beginning on somite V, on which each branchia is a simple slender 

 filament. The brancliia of somite VI has a single branch; on somite VII the 

 branches are abruptly more numerous, reaching ten; on subsequent somites 

 the branchiae acquire branches increasing in number and length; the stem typi- 

 cally stout, distally acuminate, pigmented and presenting an annulated appear- 

 ance, arising from base of notocirrus; filaments unilateral in arrangement, or 

 occasionally with one small branch inserted on opposite side distally, on branchia 

 of twenty eighth somite, near twenty-one in number. The filaments decrease 

 again in number caudad, the last branchiae, which occur on somite XLIII, 

 having but two filaments each. The branchiae are long, much exceeding the 

 middle of dorsum excepting at ends of branchiate region, the dense tufts of fila- 

 ments largely concealing the dorsum. In a paratype from Sta. 3417 the first 

 branchiae, i.e., those of somite V, have numerous branches, but on posterior 

 somites the number gradually decreases. In paratypes branchiae may occur 

 as far back as the sixtieth somite. (Plate 54, fig. 4, 5). 



The acicula are yellow with the central fibrillae darker. They are stout, 

 distally acuminate and slightly curved distally; medulla conspicuously fibril- 

 late; they are mostly two in number. Anteriorly they scarcely protrude from 

 the tubercle, but on the posterior segments they protrude conspicuously. The 

 setae arc nearly colorless, being of a weak yellowish tinge. They are of the usual 

 four kinds. A dorsal tuft arising in connection with the acicula is composed 



