NEMERTEANS 



in this species is intermediate between that described above for C. 

 frenata, where these glands occur in the integument only, and C. 

 rubra? where they occur not only in the integument and around the 

 rhynchodseum, but are thickly massed in the cephalic musculature as 



well. 



Blood and Nephridial Systems. Cephalic blood lacunae and lat- 

 eral vessels as in other species. Rhynchoccel vessels peculiar in that 

 they do not appear in the anterior fourth of the esophageal region, and 

 extend for only a short distance, terminating posteriorly in front of the 

 anterior end of the nephridial system. During their short extent, 

 however, they show numerous connections with the lateral vessels. 

 The nephridia are of the normal type for the genus, with a main canal 

 above the lateral blood vessel on each side. Anteriorly the canal 

 branches out on the wall of the blood vessel as usual. The nephridia 

 are of very limited extent, and occupy less than the middle third 

 of the esophageal region. Posteriorly each of the main canals exhibits 

 a sac-like enlargement, with highly columnar epithelium, from the 

 dorsal wall of which the efferent duct leads to a dorso-lateral aspect 

 of the body as usual. The efferent duct is not an open tubule, how- 

 ever, but spreads out in the external circular muscular layer into a 

 broad, spongy meshwork, from which a small duct leads to the sur- 

 face. 



Nervous System. Ventral commissure of brain even more massive 

 than in most related species. Large and numerous cephalic nerves 

 extend throughout the tissues of the head. Dorsal and buccal nerves 

 are also of large size. 



Cerebral Sense Organs. Much less highly differentiated than in 

 any other species of the genus yet described from the region. Ciliated 

 canals wanting, the sense organ consisting simply of an oval area 

 with differentiated sensory cells of smaller size and with longer cilia 

 than elsewhere, and provided with a rather large nerve from the dorsal 

 ganglion which lies adjacent, and just beneath the well-developed base- 

 ment layer. The region is always conspicuous by the absence of the 

 deeply staining glands which are found elsewhere on the body. Thus 

 the cerebral sense organs differ but slightly in their histological features 

 from the lateral sense organs found in the vicinity of the nephridiopores. 



Lateral Sense Organs. Small, but very sharply defined. They 

 are situated on the lateral margins of the body immediately posterior 

 to the nephridiopores. The sensory epithelium is made up of slender 



^oe, Proc. Wash. Acad. Sci., in, p. 14, pi. ix, fig. i, 1901; also previous 

 article, paged identically. 





