854 PROCEEDINGS OF THE ACADEMY OF [DeC, 



The peristomium is longer dorsally than ventrally and is marked 

 with longitudinal creases which are continued on to the base of the 

 proboscis. Somite II is as long as the prostomium and ec^uals the com- 

 bined length of III and IV. Succeeding segments are again slightly 

 longer and are distinctly annulated. In the posterior thoracic region 

 the segments are divided by the setigerous tubercles into dorsal and 

 ventral halves, the latter being again divided into a posterior larger 

 and two anterior smaller annuli. Abdominal segments are annulated 

 both dorsally and ventrally. 



Three pairs of branchi^ occur on somites II, III and lY. Each is 

 composed of numerous slender filaments having a length about one-third 

 of the diameter of the body and sessile in a close tuft. The first con- 

 tains about thirty, the second twenty-five and the third fifteen, but the 

 number in each is probably greater in perfect specimens. 



Ten ventral plates occur on the somites IV to XIII ; the anterior ones 

 are obscure, the posterior distinct. All are very short, about one-fourth 

 to one-sixth as long as wide. 



Setigerous tubercles number seventeen, and occur on somites IV to 

 XX inclusive ; though connected with the side of the body by an integ- 

 umental fold they are very mobile, and the flattened, obliqvie tufts of 

 setse project prominently in various directions from near the dorsal end 

 of the uncinigerous tori. Posterior tufts are broader and more mobile. 



Anterior uncinigerous tori are long and narrow, extending over about 

 one-sixth of the circumference of the body and separated ventrally by 

 twice their length. Without becoming shorter they gradually ap- 

 proach ventrally until the intervening space is less than one-third their 

 length. On the abdominal segments the tori are much more prom- 

 inent and have a free ventral angle and a thin membranous wing arising 

 from the dorsal l)order. This wing is gradually reduced posteriorly 

 coincidently with a decrease in the size of the parapodium, but remains 

 fairly prominent to the last. 



What appears to be a slit-like sense organ is present on somite III 

 below the'gill. Small papilla occur ventral to the seta? tufts of Yl, Yll, 

 VIII and" IX. 



The setse are all slender, nearly colorless, longitudinally striated, 

 slightly curved and winged, and taper to very acute tips. In each tuft 

 they are arranged in two rows of twelve to fifteen each, those in one 

 row having longer and narrower wings (fig. 12), the others having them 

 shorter and broader (fig. 11). 



The uncini are arranged in a single series on the tori of somites \'^ to 

 X, are partly doubled on XI and completely in two series on XII to 



