238 PROCEEDINGS OF TPIE ACADEMY OF [April, 



the aspect of a clear, translucent, bluish line. There is no diminution 

 in the length of the posterior setigerous segments, but the achsetous 

 segments are considerably reduced in both length and diameter. They 

 are terete, about twice as long as thick, have the surface deeply wrin- 

 kled transversely and bear rather prominent tori in the posterior one- 

 third. Following these is the campanulate pygidium which has a 

 narrow ringed base and a deep cup-shaped body, the margin of which 

 is divided into thirty-nine very regular bluntly rounded teeth, the four 

 ventralmost of which are considerably broader than the others, while 

 at three other points one of the latter has been replaced by two smaller 

 ones. Both without and within the surface of the cup is longitudinally 

 fluted, and in the deeper part of the interior numerous fine ribs, usually 

 two to each marginal tooth, pass to the margin of the very large anus. 



Somite II bears capillary setse only, which arise as a narrow vertical 

 tuft from a slit-like cleft into which they are retractile. Succeeding 

 segments, to XIX inclusive, bear both setse and uncini which are 

 strictly lateral in position, the dorsal interval between the setse scarcely 

 exceeding the ventral interval between the uncini. As far as somite 

 VIII the setae continue to occur in the form of vertical tufts retractile 

 within slit-like pockets; and the uncini, which begin immediately 

 below the setse and lie in the same plane, form strictly linear series 

 sessile or even depressed below the surface. On IX and all subsequent 

 segments the setse are situated on rather prominent wart-like papillse 

 in the form of crescentic tufts open below ; and the uncini are elevated 

 on the crests of swollen tori. On II, III and IV the parapodia are 

 situated in the anterior one-third; on V and VI they are but little 

 anterior to the middle; on VII, VIII and IX they are again near the 

 anterior end ; on X they shift abruptly to the posterior one-third and 

 so remain to the last. The posterior tori are especially prominent. 

 Whether XX is normally setigerous cannot of course be determined 

 until additional specimens are known. 



The number of uncini increases toward the posterior end, the counts 

 being 22 to 26 on III, 35 to 42 on V, 45 to 50 on X, 53 to 57 on XV 

 and 60 on XIX. 



The setse are numerous and form dense tufts. On II those of one 

 series are shorter and about three times as thick as the others and have 

 well-developed wings. Those in the other series are slender and nearly 

 wingless. On succeeding somites all of the setse become much more 

 elongated and more slender, but do not differ otherwise, and appa- 

 rently lack altogether any lateral hairs or awns. 



As indicated above uncini (fig. 31) are numerous on all segments; 



