'[25] FAUNA OF OUTER BANKS, VINEYARD SOUND, ETC. 665 



syUis, sp., Pcpdophylax longiceps V., etc. The Nereis megalops Y., both 

 in the heteronereis-form {Nectonereis) and in the nereis-form {N. alacris 

 v.), frequently occurred in our night excursions, and in September the 

 young of the latter of all sizes, from those with only six or eight seg- 

 ments up to those that were 10™™ or more in length, occurred abund- 

 antly at the surface. These young are very active, translucent, and nearly 

 white, with small, red specks over the surface. A very interesting new 

 species, Acrocirrns Leidyi Y.,* belonging to a genus hitherto not re- 

 corded from our coast, was taken at the surface several times this year, 

 and also iu 1881. Podarlte ohscura Y. was often abundant at the sur- 

 face, as well as in the soft mud, among eel-grass, in the harbor. Among 

 other surface Annelida were Cirrhinereis phospJwrea Y. and G.fragilis, 

 and a species of Prionospio, probably identical with P. tenuis {Spiopha- 

 nes tenuis Y., 1880). This was also taken from the harbor mud, in shal- 

 low water, last year. When perfect it has four pairs of gills, all fringed 

 on one side (Tr. Conn. Acad., iv, pi. xix, Fig. 7). A singular larval 

 form, probably belonging to this species, occurred once (September 9) 

 at the surface. 



Among the various larval forms of Annelids we were fortunate iu ob- 

 taining a very large number of Chcetopterus pergamentmeus, in various 

 stages, from very young ones up to those having the adult characters 

 distinctly developed. Of these Mr. Emerton made an excellent series 

 of drawings. The adults of this interesting species were dug from the 

 sand just below low- water mark, at Naushon I.,f by our party. The 



median largest and farthest apart, close to sides of head. Pharynx narrow, straight, 

 a little swollen anteriorly, with a well-marked tooth close to the front edge ; stomach 

 oblong, occupying two or three segments, according to their extension ; intestine with 

 two rounded lobes, close behind stomach. Setae with a rather long, flat, blade-like 

 article, strongly fringed on the edge, with the tip distinctly bidentate, and not very 

 slender ; long, capillary, sexual setae begin (when present) on the ninth setigerous 

 segment, and continue on thirteen to seventeen. The eggs and yonng are carried on 

 these same segments, usually four to each segment. Some examples (op. cit., pi. 25, 

 Fig. 2) similar iu other respects, have no sexual setae and only two eggs to a segment. 

 Three to eight hind segments are without sexual setae and eggs. Length, 3"™ to 4""™. 

 Surface, Newport, R. I., 1880; Wood's Holl, Mass., July 28 to September 12, 1881, 

 1882. Described from life. 



* Acroeirrus Leidyi Yerriil, Trans. Conn. Acad., iv, pi. 19, Fig. 2.— Body slender, 

 with distinct segments, covered with small papillfe. Head changeable, usually 

 rounded, obtuse ; eyes four, the front pair very minute ; hind pair larger and wider 

 apart ; two large, long, usually clavate antennae on front of head, near together. A 

 pair of large, long, clavate cirri on first four segments, like the antennae, but larger, the 

 length three or four times the breadth of body. Ventral, compound setae, with a very 

 long, curved and hooked terminal article, begin singly on the second segment bear- 

 ing cirri ; long, slender, capillary dorsal cirri begin singly on the fourth segment, but 

 form fascicles of six to nine farther back. Color dark olive-green to dark brown ; cirri 

 and antennae paler green with yellow tips. Length, lO""™ to 15°"" ; diameter of largest, 

 about l""™. Wood's Holl, surface, evening, August 2 to September 9, 1881, and 1882, 

 Described from life. 



t This species was first discovered at this place in 1880 by Mr. Charles Webster and 

 Mr. Vinal N. Edwards, from whom I received specimens at that time. 



