416 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 10 



The first segment is achaetous and apodous. Segments 2 to 12 are pro- 

 vided with notopodial and neuropodial fascicles, the first pair already 

 well developed. Lateral organs are small but present from the first 

 setigerous segment; they are located between notopodia and neuropodia 

 and slightly nearer the former. 



In the abdomen the ventrum is flat, solelike and the dorsum is increas- 

 ingly arched upward in posterior segments. Neuropodial tori are long in 

 a tranverse direction; they extend ventrally so that the 2 of a segment 

 approach each other midventrally (pi. 51, fig. 4). The superior portion 

 of the ridge is highly vesicular and branchial, already from the first; by 

 the thirteenth or fourteenth abdominal segment it comes to be a long 

 simple lobe which continues so through at least 18 segments (a posterior 

 portion is lacking). These branchiae are not retractile; they are merely 

 prolongations of the superior part of the neuropodial torus. 



Lateral organs in the abdomen are low, ovoid papillae located just 

 above the inflated neuropodial lobe; they are visible in this position 

 through the known length (about 47 abdominal segments). Notopodial 

 tori are seemingly absent from the abdomen. Instead, the epithelium is 

 thin, inflated and the longitudinal muscles are visible through the body 

 wall around the dorsal and lateral portions of the body. 



Nephridial apertures are present in the thorax and abdomen. In the 

 former they are to be found in the segmental grooves, between the seventh 

 and eighth setigerous segments, about half way between notopodia and 

 neuropodia and are continued posteriorly to between the eleventh and 

 twelfth segments. In the abdomen they are on the first 3 segments, im- 

 mediately in front of the lateral organ. 



Hooded hooks are long handled; the shaft is coarsely and distinctly 

 fibrillated. The distal end terminates in a bifid beak with a voluminous 

 hood that fits loosely about the beak. The fang is strong, large and 

 directed slightly downward. It is surmounted by 3 or 4 teeth in a single 

 row; the fourth tooth may be lacking and if present is usually a smaller 

 one at the end of the series. The large hood is more nearly like that in 

 A^. magnus (see above) than in any other species examined. 



"N. lobatus is characterized by its peculiar simple, lobed, nonretractile 

 branchiae that are prolongations of the superior neuropodial ridge; they 

 are present from about the fourteenth abdominal segment and continued 

 posteriorly. Notopodial abdominal tori are believed to be absent. Hooded 

 hooks have a large, loosely fitting hood ; the crest consists of a transverse 

 row of 3 or 4 small teeth. Lateral organs are visible on all known seg- 



