120 Thirty-second Report on the State Museum. 



STREBLOSPIO n. gen. 

 Head conical ; proboscis incomplete above, divided below into two lobes 

 along its anterior part. First segment prolonged laterally and below nearly to 

 the front of the head; above carrying one pair of tentacles and one pair of 

 branchiae. Second segment with raised dorsal membrane, forming a pouch. 

 Dorsal setae capillary. Ventral setae of first six segments like the dorsal, after- 

 wards both uncinate and capillary. Anal segment simple, without appendages. 



Streblospio Benedicti n. sp. 



PLATE V, FIGS. 48-50. 



Head, in extension, pointed, conical; posterior half somewhat compressed, 

 sharply convex ; anterior half slightly depressed. 



Proboscis deficient above, below divided into two lobes for about one-half its 

 length ; these lobes are triangular at base, but (in extension) terminate, each in 

 a short, finger-shaped process, covered with numerous long cilia. The first seg- 

 ment is about the length of the following segments, dorsally ; at the sides and 

 below it is prolonged, forming a kind of hood for the head. This hood or 

 sheath originates as a thin, almost membraneous elevation of the sides of the 

 segment, just within the dorsal setae, passes forward external to the bases of the 

 tentacular cirri and branchiae, is prolonged to near the apex of the head, then 

 curves suddenly downward, presenting a thin, free, anterior margin ; laterally 

 it is closely applied to the head, but rises above it, presenting a free, upper 

 margin on each side ; the head projects but very little beyond its hood. Dor- 

 sally the anterior margin of the first segment is concave, and carries a minute, 

 conical, median papilla or cirrus. 



Tentacular cirri (tentacles) have the same structure as in Polydora ; turned 

 backward they reach to the eighth or ninth segment. 



Branchiae behind and a little within the tentacles ; reach back to the seventh 

 or eighth segment ; widest in the middle, tapering uniformly in both directions, 

 except that near the top they are suddenly constricted, ending in a short cylin- 

 drical process ; they are flattened below, carinate above, giving a triangular 

 cross section for most of their length ; edges thin, and thrown into deep, 

 rounded folds or scollops. Both tentacles and branchiae are densely covered 

 with long cilia ; turned forward they completely cover the head ; the setae of 

 the first segment, both dorsal and ventral, are similar to those of the next five, 

 but are a little shorter. 



Second segment, covered dorsally by a raised membrane, forming a pouch ; 

 the free anterior margin of this pouch is deeply concave ; its elevation above 

 the dorsum equal to the thickness of the body ; at the sides it passes into the 

 dorsal cirri (lobes). 



Dorsal cirri : back of each fascicle of dorsal setae, on the first ten segments, 

 is a broad, rounded plate or lobe ; back of the tenth segment 'this plate gradu- 

 ally becomes narrower, until it is changed into a short, conical cirrus, which 

 remains to the end. 



Ventral cirri : on the first six segments behind each bunch of ventral setae is a 

 lobe similar to the dorsal lobe, but smaller ; at the seventh segment it disappears. 



