240 PROCEEDINGS OF THE ACADEMY OF [April, 



lips. Mouth bounded behind by III which is united with IV to form 

 the rugous posterior Hp. Remaining segments few, large, distinct, 

 strongly differentiated by deep furrows below and more shallow ones 

 above; lateral borders deeply and coarsely serrated; entire ventral 

 surface and median dorsal (interbranchial) field cjuite smooth. Seg- 

 ments increase in size to XI, then gradually decrease to the small 

 bilobed pygidium which bears a pair of thick, truncate, cylindrical, 

 appressed cirri about as long as the lateral tentacles. 



Parapodia simple but rather prominent, lateral swellings producing 

 the coarse lateral serrations, biramous, the notopodial and neuropodial 

 tubercles widely separated and each bearing a large setigerous sac 

 with elliptical orifice and an eversible rim, the notopodial orifice facing 

 laterad and slightly dorsad and caudad, the neuropodial laterad and 

 caudad. Toward the ends the parapodia become smaller and the 

 setse tufts gradually reduced; the anterior ones shift toward the dorsum, 

 the first or peristomial foot being strictly dorsal; approaching the 

 caudal end the setae fascicles are directed more and more caudad. 



Notocirri arise at the caudo-dorsal border of the notopodial tuft 

 of setse and reach to the base of the corresponding cirrus of the opposite 

 side or on posterior segments beyond it. Cirrophores long, slender, 

 terete, nearly as long as the segments to which they belong; styles 

 flagelliform, three to three and one-half times as long as the cirriphores. 

 Neurocirri arise within the lips of the setae sacs on the ventral side of 

 the neuropodial fascicle; they consist of short and obscure cirrophores 

 and long, slender, fragile, flagelliform styles equalling the notocirri on 

 middle segments, but diminishing in size posteriorly and also anterior 

 to V. The first three parapodia have the cirri relatively short and 

 stout, the notociii'us considerably shorter than the neurocirrus. They 

 also possess a third much smaller cirrus situated immediately dorsal 

 to the notocii'rus and probably representing the gills; they are similar 

 to the notocirri and that on the peristomium is longest. 



Branchiae begin on somite IV and continue, gradually diminishing 

 in size, to the caudal end. They arise on the posterior border of the 

 dorsum of their segments, separated by about one-third of the total 

 width, and lie nearly flat on the dorsum, reaching caudad over the 

 succeeding segment so that they are slightly imbricated. Form 

 broadly suboval, lamellar, bipinnatifid; composed on middle seg- 

 ments of a tapered and somewhat sinuous axis bearing alternately 

 on each side about eight simply pinnate branches diminishing in size 

 and complexity distally, where the series is completed by two or three 

 simple pinnae. Toward the ends of the body they become smaller, 

 with a diminished number of Dinnae. 



