302 



BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



Pi'oboscis pale llesh color, of large size as compared with body of 

 worm, provided with nine, or occasionally ten nerves. Basis of 

 central st^det somewhat elliptical and only a little wider posteriorly 

 than near attachment of stylet. Basis measures about .07 mm. in 

 length and is about two and one half times as long as broad (Text- 

 fig. 62). Posterior half of basis granular and dark, 

 becoming more translucent anteriorly. Central 

 stylet slender, aboiit two thirds as long as basis ; 

 usually with two accessory stylets in each of the 

 two lateral pouches. 



Cephalic gla7ids voluminous, situated both above 

 and beneath rhynchodaeum, and reaching back 

 nearly to the brain. 



Pigment of dorsal markings situated in integu- 

 ment. 



AVmientary canal. — A pair of rather large 



diverticula of the intestinal caecum extend forward 



to doi'sal side of brain, uniting shortly behind the 



mouth to form a broad, unpaired caecum with 



lateral diverticula beneath the stomach. 



Nephrldia limited to brain region, the tubules extending beside, 



as well as a very short distance behind, the ganglia ; with a single 



pair of efferent ducts opening laterally just opposite posterior ends 



of dorsal ganglia. 



Cerebral sense organs I'emarkably large ; situated beside and 

 beneath the ventral ganglia, and projecting somewhat in front of 

 them. 



Habitat. — Common on piles of wharf at San Pedro, California. 

 Sexually mature in August or September. Sexual glands volumin- 

 ous, extending anteriorly well toward brain region. Ova of large 

 size (about .18 mm, in diameter), pale ohve green in color, arranged 

 in a single row along each side of intestinal region. 



Fig. t)-.i. — Tetra- 

 stemrna reticu- 

 laturn. Outlines 

 of central stylets 

 and bases in two 

 individuals. 



(S4. Tetrastemma caecum Coe. 



Proc. Wash. Acad. Sci., 3, p. 59, 1901 ; ITarriman Alaska Expedi- 

 tion, 11, p. 59, 1904. 



PI. 22, fig. 151. 



This minute species is especially remarkable, and quite aberrant 



