coe: nemerteans of west and northwest coasts. 303 



from most other forms of the genus, both in lacking ocelU and in 

 being hermaphroditic. 



Body rounded, of about the same diameter throughout ; of minute 

 size, being but 5 to 10 mm. in length and 0.5 to 1.0 mm. in diameter 

 when sexually mature. 



Ocelli completely wanting. 



Color whitish or very jjale yellowish with darker intestinal lobes. 



Proboscis of enormous size when compared with that of body, 

 when everted being practically equal to the diameter of the body 

 itself (PL 22, fig. 151). Central stylet and basis very slender and 

 delicate. Two accessory pouches each contain two or three slender 

 stylets. Nerves more or less confluent. 



Intestinal caecum extends forward well toward brain. 



Cerebral sense organs remarkably voluminous as compared with 

 other organs of head ; situated immediately in fi-ont of brain and 

 extending posteriorly on ventral side of brain lobes as far as ventral 

 commissure. 



Reproductiiie organs. — This species resembles T. kefersteini 

 Marion in being hermaphroditic. The latter species is commonly 

 parasitic in the mantle cavity of the tunicate Phallusia (Marion, 

 '74) , and it is possible that the present species commonly lives in a 

 similar position in some Alaska tunicate. 



Sexual products are mature in July. Ova are very large, fully 

 two thirds the diameter of the body, and hence are arranged at 

 irregular intervals in a single row (PI. 22, fig. 151). Spermaries 

 often alternate very irregularly with the ova, or may be grouped 

 irregular^. Ova and spermatozoa are not usually mature at the same 

 time in the same individual. When ova are mature spermaries are 

 small, and when spermaries are mature and their ducts fully formed 

 the ova are but half grown. 



Spermaries usually open dorsally, but the exit of an ovum must 

 cause a large break in the body walls. Marion ('74) considered it 

 probable that in 7'. kefersteini deposition of the ova resulted in the 

 death of the worm, and I have little doubt that this is often the case. 

 The presence of immature spermaries in the worms with mature 

 ova, however, makes it probable that some of the worms can sur- 

 vive the process of egg laying. It is possible that internal fertili- 

 zation may take place in at least a portion of the individuals, as in 

 the hermaphroditic Stichostemma. 



