No. 104.] 149 



Branchiae begin on seventh segment, long, finger-shaped, color- 

 less, with red center ; they are found on all segments after the sixth, 

 except a small but variable number of posterior segments. 



Setae of the fifth segment (fig. 46) eight to twelve in number, 

 stout, apex bluntly rounded and slightly curved; a little below the 

 apex is a small tooth on the side of the seta, forming a very small 

 angle with the seta ; dorsal setfe long, capillary, longer behind than 

 in front ; ventral sets (fig. 47) short, bidentate ; inner tooth very 

 long, sharp, given off at right angles to the body of the seta ; outer 

 half covered by a membrane. 



Terminal sucker broad, shallow, white ; anal opening surrounded 

 by low papillae. 



Body colorless, except as colored red or brownish-red by the blood 

 and contents of the intestine ; on either side of the carina a brown 

 line, diverging in front, and passing to the outer base of the tentacles. 



Length, 1-4™™ ; segments numerous. 



Found on water-soaked wood, living in crevices, etc. 



Tubes made of dirt, fragile, constructed with great rapidity. 



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 setfe capillary. Yen- 

 tral setffi of first six segments like the dorsal, afterward both un- 

 cinate and capillary. Anal segment simple, without appendages. 



Steeblospio Benedicti n. sp. 



PLATE (v), viii, 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 ex- 

 tension) terminate, each in a short, finger-shaped process, covered 

 with numerous long cilia. The first segment is about the length of 

 the following segments, dorsally ; at the sides and below it is pro- 

 longed, 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 set®, passes forward external to 

 the bases of the tentacular cirri and branchite, 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. Dorsally 

 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 Poly- 

 DORA ; turned backward they reach to the eighth or ninth segment. 



