236 PROCEEDINGS OF THE ACADEMY OF [April, 



podia. Segments 32 to 34, strongly differentiated ventrally by deep 

 furrows which are well-marked dorsally also, except in the median 

 area where they become obsolete in a series of biconvex intersegmental 

 areas. Median naked field about one-fifth total width of dorsum, the 

 parapodial areas densely covered with rows of branchiae and setae and 

 occupying the rest of the dorsum, ^^entrally a slight neural gi'oove 

 runs from the posterior lip to the pygidium. Pygidium minute, 

 situated between the last pair of posteriorly directed parapodia and 

 bearing a pair of appressed vertical lamellar anal cirri with thickened 

 borders. 



Parapodia of the usual form, the notopodia sessile and dorsal; 

 neuropodia lateral, slightly projecting, low lamellae, overlapping the 

 ventral end of the notopodia from behind. Cirii usually about equal 

 to gills in length, but sometimes slightly longer or shorter, rather stout, 

 gently tapered. Notocirrus usually the shortest of the three, reaching 

 only slightly beyond the middle line and situated slightly mediad of the 

 setae palisade and a little anterior to the branchiae. Middle cirrus in 

 line with notocirrus and opposite interval between third and fourth 

 or fourth and fifth gills from the dorsum. Neurocirrus similar, situated 

 just within the postero-ventral margin of the neuropodial fascicle 

 of setae. 



Branchiae borne on all setigerous segments, usually ten (but sometimes 

 nine or eleven) pairs on middle segments, the three ventralmost in the 

 interramal area much crowded and often in actual contact or even 

 with their stems partially coalesced. Each gill (PL XV, fig. 12) 

 consists of a well-defined, stout stem bifurcated into a pair of nearly 

 symmetrical trunks which divide dichotomously three or four times 

 and end in rather slender, cylindroid, pointed filaments often half the 

 total height of the gill. The angles of bifurcation are wide and the 

 branching spreading in a plane so that the twigs of neighboring gills 

 intercross. In the oral region the number of gills is somewhat reduced, 

 and on somite I there are only six pairs with more or less coalesced 

 bases and rather short filaments often thickened in the middle. The 

 latter condition sometimes appears on other gills, but usually the 

 filaments are extended and of regular diameter, 



Notopodial setae (PI. XV, figs. 13-15) arranged in a long palisade of 

 three rows running the entire length of the gill series. All are hollow, 

 brittle, calcareous, translucent and white, or the granular contents 

 of some of the larger ones slightly yellowish. All are relatively short 

 and few project beyond the ends of the gills. Serrate bifid setae are 

 unusually numerous and appear not only to make up the anterior 



