122 bulletin: museum of comparative zoology. 



blood vessel on each side but of very limited extent, occupying less 

 than the middle third of esophageal region. The efferent duct, 

 leading from a sac-like enlargement at the posterior end of main 

 longitudinal canal to dorsal surface of body, spreads out in the 

 external circular muscular layer into a broad, spongy mesh-work, 

 from which a small duct leads to the surface. 



Cerebral sense organs but little specialized, without ciliated 

 canals, consisting simply of an oval region Avith differentiated sen- 

 sory cells of smaller size and with longer cilia than elsewhere, and 

 provided with rather large nerves from the adjacent dorsal gangUa. 

 Cerebral sense organs differ but slightly in their histological features 

 from the lateral sense organs, but the region is conspicuous because 

 of the absence of deej^ly staining glands. 



Lateral sense organs small, but very sharply defined ; situated on 

 lateral margins of body immediately posterior to nephridiopores, 

 appearing in life as rounded pits of paler color exactly on margins 

 of body on anterior border of third wliite ring ; sensory epithelium 

 made up of slender cells presenting a sharp contrast to neighboring 

 cells of integument because of their comparative freedom fi-om 

 secretion. 



Habitat. — Monterey Bay, California ; apparently a rare species, 

 occurring from low water to 15 fms. or more on soft bottom. Sex- 

 ual products mature in September. 



7. Carinella pellucida Coe. 

 Trans. Connecticut Acad. Sci., 9, p. 515, 1895. 



Body very slender, almost filiform when fully extended, rounded 

 throughout, or slightly flattened posteriorly. Head rather broad, 

 often eraarginate m front, flattened dorso-ventrally and marked off 

 from body by slight lateral constrictions rather less distinct than in 

 related species of genus. Resembles (Jarinella linearis Mcintosh 

 rather closely externally, but differs in many respects in internal 

 anatomy, as noted below. Resembles CephalotJirix linearis also in 

 color, size and general shape of body, except head, but can readily 

 be distinguished by position of mouth, by shape of head, and by the 

 fact that it does not coil the body in a spiral. 



After preservation a conspicuous brown or blackish band appears 



