168 THE ANNELIDA POLYCHAETA. 



AUTOLYTUS OBLIQUATUS, Sp. nOV.^ 



Plate 19, fig. 8; Plate 20, fig. 1-3. 

 Epitokous Male (Polybostrichus). 



The body in general is colorless and translucent, in life probably trans- 

 parent, the only dark parts being the eyes and the first six setigerous somites, 

 which are darkened from the masses of spermatozoa confined to them. - 



The average length is near 6.5 mm. Exclusive of the parapodia, the body 

 is widest in the anterior or seminiferous region, the body immediately behind 

 this being abruptly narrower, typically thereafter again gradually widening 

 over eight or ten somites and then very gradually and continuously narrowing 

 to the caudal end, where it is slender and pointed. The number of somites 

 in the anterior division, that is, the division in front of the first somite bearing 

 long natatory setae in addition to the short ones, is constantly eight, six of which 

 are setigerous; and in the posterior division typically thirty-three, making the 

 total number forty-one. 



The prostomium is broad, laterally convex, with the anterior margin 

 incurved between the bases of the palpi. The palpi, fused with the bases of the 

 tentacles excepting distally, are proximally thick, swollen, bulging, and in con- 

 tact with each other mesally, or nearly so, and narrowing distad. A little above 

 the base each is always bent abruptly ectad. Palpus and antenna on each side 

 separating near middle of total length, -with each branch cylindrical, gently 

 narrowed distad, narrowly rounded at tip, and with numerous short annuli 

 which are not very strongly marked. The minor paired tentacles are situated 

 dorsally between the eyes, each in line with the corresponding palpus and at 

 an anteroposterior level midway between the two pairs of eyes; each is short, 

 cylindrical or somewhat compressed, and distally rounded. The median ten- 

 tacle is attached caudad of the eyes between the tentacular cirri. It is stout 

 at base, tapering distad to a fine tip; it is long, reaching to the seventeenth or 

 eighteenth somite (fifteenth or sixteenth setigerous). As usual, two pairs of 

 eyes. The posterior eyes dorsal in position, strongly, subconically elevated, 

 with the lenses directed dorsad, small. The anterior eyes are much larger; 

 they are a little farther forward and are on the ventral side of the head, strongly 

 elevated, and with the lenses directed almost strictly ventrad. (Plate 20, fig. 1,2). 



' oblic]uan', to bend to the side, 



