1903.] NATURAL SCIENCES OF PHILADELPHIA. 447 



crowds the much reduced parapodium dorsad, until by XV it is directed 

 upward and quite invisible from below, but a reverse change sets in by 

 XXX, and, with the final disappearance of the glandular area, the 

 parapodia again become quite lateral in the posterior half of the 

 body. By XV also the postsetal lobe has become a small inconspi- 

 cuous process, but the dorsal cirri, although somewhat reduced, re- 

 main always prominent. 



Branchiae prominent but simple, arising from a common base with the 

 dorsal cirri, and when fully estabhshed appearing as the direct continu- 

 ation of that base, of which the cirrus has more the aspect of a lateral 

 branch; they are erect and long enough to just reach middle line of 

 back when best developed. Sometimes they are foreshadowed by a 

 bifurcation of the dorsal cirrus of the 4th parapodium, but normally 

 appear abruptly on the 5th as a slender filament equalling the cirrus in 

 length, but quickly increase to a considerably greater length, and con- 

 tinue with no change except a slight decrease in size as far at least 

 as the 110th setigerous somite. As the posterior 44 somites show no 

 trace of branchiae it is evident that this species must reach a length 

 quite remarkable for the genus. 



With the exception of the posterior hooked acicula, which are rela- 

 tively stout and pale yellow, the setae are delicate and colorless. Com- 

 pound hooked setae are confined to the first 3 parapodia in all the speci- 

 mens examined with reference to this point, and, with the exception of 

 2 or 3 slender pointed dorsal setse, are the only kind present in the first 

 parapodium; end piece with 3 processes, the terminal one longest; 

 guard prolonged into an acute tip which reaches far beyond the body 

 of the seta. 



Slender, capillary setae are present in all the parapodia, but in small 

 number in the first 3, while from the 4th to about the 10th they are 

 the only kind occurring, and are somewhat larger, with more evident 

 serrate wings. Parapodia of the middle region each bear a tuft of 

 such setae projecting from the dorsum of the foot in a strongly dorso- 

 lateral direction above the hooked uncina. 



Raddle-shaped setse are first detected on the 10th parapodium, on 

 which 1 appears, while posteriorly 4 or 5 occur between the capillary 

 setae and the hooked aciculum. They are very delicate and easily over- 

 looked, with slender, somewhat curved stems and obhquely truncate, 

 slightly curved terminal blades bearing about 16 deUcate spines, and 

 marked with as many converging striae. 



In addition to the ordinary acicula, each neuropodium, beginning at 

 about the 10th or 12th, is provided with 2 pale yellow uncina with 



