[29] ANNELIDS OF PROVINCETOWN, MASS. 727 



with a narrow lateral space, depressed, flattened; the remaining part of 

 the head somewhat elevated. 



Eyes small, black ; variable both in number, position, and form ; not 

 the same in any of these respects on any two specimens. 

 . Tentacles of the form usual in this group, rather stout, reaching back 

 to the eighth segment, tapering slightly, the diameter at the apex be- 

 ing about one-half that at the base. 



The buccal segment is very large, reaching in front to the anterior 

 margin of the head; at the sides and behind extending far beyond the 

 head ; it has both dorsal and ventral rami, of the same form as those of 

 the next segment, but not quite so large. 



The dorsal rami of the non-branchiated segments consist of an ante- 

 rior, low, rounded, lobe; and a posterior, somewhat elongated and flat- 

 tened, cirrus. 



The ventral rami of the first ten segments do not differ materially 

 from the dorsal rami ; after the tenth segment the ventral cirri grow 

 progressively smaller and disappear; the anterior lobe, now become 

 lateral and transverse, is lengthened and depressed (tig. 55). 



On the branchiated segments nothing remains of the dorsal ramus 

 but a conical elevation from which the setae arise. 



The branchiae begin on the thirteenth segment (fig. 55). They are 

 slightly wider at either extremity than in the middle, apex very widely 

 rounded; outer margin with a wide membrane reaching from base to 

 apex; inner margin, as well as an elevated membranous ridge uniting 

 the bases of the opposite branchiae, with very long, densely crowded cilia ; 

 on the largest specimen taken there were 23 pair of branchiae followed 

 by 15 non-branchiated segments. 



The setsB of the first eight segments are all capillary, mostly long and 

 delicate; those of the dorsal rami longer than the ventral. In botli 

 rami are a few shorter setae, somewhat wider along their inner two-thirds 

 (fig. 56). 



The dorsal setae of the branchiated region are a little shortened, but 

 back of the branchiae grow long again, and are even more delicate than 

 in front. 



On the 9th segment the ventral setae are changed to hooks (fig. 58), 

 of which there are from 4 to 7 in each rami ; they project but slightly be- 

 yond the setigerous lobe, and are covered by a delicate membrane. 



The anal segment ends in four short, stout, bluntly conical lobes (fig. 

 59). The body is flattened above, convex laterally and below. Im- 

 pressed lines, runniug along the ventral surface, include the middle 

 half of this surface; these, being crossed by the lines of segmentatiou, 

 furnish median ventral plates. 



The extended proboscis was not seen. 

 ■ The posterior margin of the mouth is crenulated ; the anterior margin 

 of the buccal segment is divided by a longitudinal median incision into 

 two rouud'.'il lobes, which may be widely separated or closely approxi- 

 mated. 



