NO. 4 HARTMAN : POLYCHAETOUS ANNELIDS 413 



proximal part, smooth and epithelial distally, but the two regions are not 

 sharply separated from each other. 



The thorax consists of 12 segments; each is biannulate and the 2 rings 

 are nearly equal. The first one (peristomium) is apodous and achaetous. 

 The second to twelfth segments have notopodial and neuropodial fascicles 

 each provided with slender, pointed setae. The first fascicles are slightly 

 smaller than those farther back but similar in other respects. Abdominal 

 parapodia are provided with hooded hooks only. They are arranged in 

 single series, in ridges that are shorter in notopodia, longer in neuropodia. 

 Notopodial tori in anterior, median and posterior abdominal segments do 

 not differ from one another except that there is a gradual decrease in 

 length posteriorly with diminishing width of body. 



Branchiae are conspicuous, tufted, retractile lobes, in median and 

 posterior abdominal segments; they are already present from about the 

 twenty-sixth abdominal segment, or on the second segment after the dis- 

 appearance of the genital pores. The first few pairs are small and consist 

 of a few eversible lobes; they are located immediately behind the outer 

 posterior side of the notopodium (pi. 50, fig. 6). Where best developed, 

 they gradually come to consist of a double tuft of about 40 or more 

 vesicular filaments; they gradually diminish in size and number of 

 branches in posterior segments. 



Nephridial pores have not been found on the thorax. They are first 

 present from the first abdominal segment and are probably continued 

 posteriorly to the end. The external aperture is in a transverse groove, 

 immediately behind the lateral organ, between notopodial and neuro- 

 podial ridges. In mature individuals, the first 20 to 24 pairs are modified 

 as genital pores. These are conspicuous in female individuals, present 

 from the first to about the twenty-fourth abdominal segment but they are 

 abruptly absent thereafter. 



Abdominal hooded hooks are long handled with shaft slightly 

 twisted. The shoulder and neck are slender and continuous. The beak 

 is sharply curved to form a large rounded crescent and a fang that is pro- 

 portionately smaller than usual ; it is flattened and terminates in a small 

 boss. The crest is a closely fitting cap, smooth on its side except for "a 

 short tranverse row of 4 small teeth above ; on its inner concave side it is 

 neatly sculptured with longitudinal crenulate ridges that number about 

 15 to 20; they terminate in short denticles. These crenulations probably 

 correspond to the teeth of other species. The secondary short row has 4 

 teeth that alternate with 5 of the crenulations in the major row. The 



