414 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
first only one or two uncini (Fig. 114) among the capillary bristles, 
gradually increasing to 4ive, while the capillary bristles decrease 
pari passu . Anal cirri two, short and stumpy. 
The present species undoubtedly belongs to the family Levin- 
seniidae recently established by Mesnil and Caullery (’98) for the 
reception of a small group of peculiar little Polychaetes which show 
affinities to the Spionidae on the one hand, and to the Ariciidae on 
the other. The species under consideration most nearly resembles 
Aricidea, of which two species have been described from the Atlan¬ 
tic coast by "Webster and Benedict (’87). It differs enough how¬ 
ever from Aricidea to deserve generic distinction. The presence of 
parapodia and setae on the peristomium probably indicates a more 
primitive character than the allied genus exhibits. The large size 
• of the eyes is also remarkable, and would seem to indicate a pelagic 
habit. 
The foregoing description is based upon a single specimen from 
iPoxt Orchard, collected by Miss Robertson in June, 1899. 
Magelonidae. 
30. Magelona longicornis sp. nov. PI. 11, figs. 115-118. 
Form cylindrical, rather stout, of nearly uniform diameter, 
divided into two regions: (1) the anterior , in front of ninth 
somite, with capillary, double-bordered setae (Figs. 115-117) in 
both fascicles; (2) the posterior, back of and including the ninth 
somite, with uncini (Fig. 118) both above and below. Ninth 
somite (Fig. 116) shorter than the others, and marked by a 
deeper constriction, with a pair of comb-like fascicles of short, stiff, 
capillary setae. 
Prostomium (Fig. 115) flattened, grooved in median dorsal line, 
anterior tip expanded; no eyes. Peristomium bears a pair of 
enormously long, flexile, tentacular cirri, beset with numerous cap¬ 
itate papillae on exterior aspect; showing rings of contraction near 
its base (Fig. 115). Proboscis (pr.) rounded, without corrugations 
or surface differentiation; extensible as far as tip of prostomium. 
Parapodia (Figs. 115, 116) of anterior region slightly developed; 
dorsal and ventral cirri small; a small branchia between them ; 
dorsal and ventral setae (Fig. 117) of same form, double-bordered 
capillary. In posterior region, branchiae and cirri are larger ; 
uncini (Fig. 118) inform of “ hooded crotchets” bidentate at tip, 
in transverse rows of ten or eleven, rising high upon dorsal side. 
