258 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



Sense organs. — The ocelli are of rather large size. Most of 

 them lie near the dorsal and lateral margins as usual, but some are 

 situated deeper in the tissues of the head and close beside the brain 

 (PI. 21, fig. 131). 



The cerebral sense organs are remarkably voluminous (fig. 131). 

 They lie lateral to the dorsal gaiiglia and close besi<le them, biit 

 extend posteriorly behind the ganglia, and abut closely against the 

 posterior faces of tlie latter. They each communicate with the 

 exterior by a large canal which passes forward in front of the brain 

 and opens ventro laterally as usual. 



Parasites. — In each of the three specimens sectioned the whole 

 body, including brain, lateral nerves, muscles, proboscis sheath and 

 proboscis, body parenchyma, basement layer, and epithelium, is in- 

 fested with countless numbers of small oval parasites which stain 

 deep blue with haematoxylin. These appear to belong to a species 

 of Gregarinae. They are about .02 mm. in length by .006 mm. in 

 diameter, and hundreds of them occur in a single section. They are 

 most abundant in the anterior portions of the body, but are present 

 quite to the tip of the tail. 



Habitat. — Fifteen specimens of this new and interesting species 

 were collected by the U. S. F. C. steamer Albatross at Isthmus 

 Cove, Catalina Island, California. The label states that they were 

 "taken in the surface net with an electric light" on April 9th, 1897. 

 Two lots of specimens contained similar labels. From this we must 

 infer that we have at hand a species of more or less pelagic nature, 

 which leaves its burrows on occasion and swims about at the surface 

 of the sea, as do some species of Cerebratulus ( C. lacteus of the 

 New England waters, for example). Indeed, the posterior portion 

 of the body is remarkably flattened, as is described above, and its 

 structure well adapts the animal for swimming. It would scarcely 

 be expected that the worms would be found at the surface, except 

 at the period of sexual maturity, unless the species were wholly 

 ])elagic, yet none of these specimens contained mature sexual prod- 

 ucts. At the same time, I do not think we are warranted in consid- 

 ering this a truly pelagic form, for the structure of the body is 

 closely similar to that of other species living under stones and in 

 burrows, and is widely different from that of other known pelagic 

 nemerteans. There remains the final possibility that the same error 

 occurs in both labels and that the specimens actually came from 



