AUTOLYTUS PLANIPALPUS. 171 



abruptly near the middle of their length at the level of the bifurcation, the two 

 branches beyond this being cylindrical, and the ventral one larger than the 

 dorsal (mesal). The annuli are short, numerous and distinct. The minor, or 

 posterior paired, tentacles are farther caudad than usual, being attached between 

 the posterior eyes and partly covered by the edges of the palpi. They are short, 

 conical and distally rounded. The median tentacle is, as usual, attached far 

 caudad between the tentacular cirri. It is stout at the base, continuously taper- 

 ing distad, and it reaches to about the twenty fourth setigerous somite. The 

 annulations are strongly marked. The eyes on each side are situated on the 

 side of the head, the posterior one distinctly caudad of the other and much 

 smaller in size. The lenses of the anterior eyes are du-ected nearly cephalad. 

 (Plate 21, fig. 1). 



The first somite has lost the tentacular cirri, scars, however, showing their 

 places of origin. 



The second somite is setigerous, the neuropodia being well developed and 

 like those of the immediately succeeding somites. It bears a pair of large 

 tentacular cirri closely similar to the median tentacle in form and size. The 

 ceratophore is short and the annulations are strongly marked. (Plate 21, fig. 1). 



The third and succeeding twelve somites are sharply set off from those 

 farther caudad. They are short and closely crowded, are dark from the con- 

 tained masses of spermatozoa and have short, conical, distally rounded para- 

 podia bearing only the shorter composite setae. The neurocirri are attached 

 at the bases of the parapodia above. They are gently tapered distad, rounded 

 at the tips, distinctly annulate, and much exceed the setae. 



The parapodia of the second division of the body are longer; they are very- 

 deep dorsoventrally but are conspicuously flattened, relatively thin, in the 

 cephalocaudal direction. Each parapodium is distally divided into two lobes, 

 of which the ventral one shows also a small secondary notch. Each parapodium 

 bears a notocirrus which is attached above near the distal end; it is tapered 

 conspicuously, is strongly annulate and is shorter than those of the anterior 

 somites. (Plate 20, fig. 4). Anal cirri missing from type. 



The composite setae of the typical parapodia are usually eight to ten in num- 

 ber, these decreasing in length from above ventrad. The shaft is of the usual 

 slightly curved form, abruptly enlarged at the distal end and with the distal 

 edge of the socket moderately oblique, the teeth fine and acute, with the most 

 distal one not especially large. The terminal piece is distally narrow, the 

 terminal part small and scarcely bidentate, the teeth small, very obtuse and 



