64 COB 



ward on each side, external and ventral to the dorsal brain lobes, nearly 

 as far as the ventral commissure. Here, at the anterior extremity of 

 each sense organ, a canal passes obliquely downward and outward to 

 open into a shallow oblique furrow on the ventro-lateral aspect of the 

 head. The sense organs are closely united with the posterior ends of the 

 dorsal brain lobes. In the middle region of the brain, the anterior ends 

 of sense organs are triangular in section, and lie external and between 

 the dorsal and ventral ganglia. Farther back a glandular appendage 

 of the sense organ pushes itself in between the internal faces of the 

 brain lobes. This appendage fuses with the ventral portion of the 

 sense organ more posteriorly. The brain lies deeply buried in the 

 tissues of the head and nearly in the median line, but the lateral nerves 

 while still in the region of the cephalic sense organs bend sharply 

 outward, and occupy throughout the remainder of their course posi- 

 tions immediately external to the circular muscular layer of the body 

 wall. 



The genital products were nearly mature in July. The oviducts 

 were in many instances preformed, and opened on the dorso-lateral 

 aspects of the body. 



Habitat. Only four individuals of this species came under my ob- 

 servation. One was collected at Cape Fox (Kincaid), two at 

 Yakutat, and the fourth at Orca in Prince William Sound. All were 

 found under stones in rather hard mud at low water. The individuals 

 contract strongly when handled, throwing the surface of the body into 

 wrinkles, and often coil the posterior portion of the body into a close 

 spiral, much as does Cephalothrix '. 



Lineus Sowerby. 

 The British Miscellany, London, p. 15, 1806. 



Representatives of this genus are characterized by a slender, some- 

 times thread-like body, usually rounded throughout. The body is 

 commonly twisted and coiled into an irregular mass. The movements 

 are sluggish. The animals creep over objects and readily move about 

 on the surface of the water, but they are unable to swim. The body 

 is extremely contractile ; the head is often slightly wider than the body, 

 of oval shape, and is usually provided with numerous minute ocelli, 

 often arranged in a single row on each side of the head. A caudal 

 papilla or cirrus, a diagonal muscular layer, and neurochord cells are 

 all wanting. The proboscis sheath is often short in comparison with 

 the length of the body. 



