82 Journal of Entomology and Zoology 



as a mere functional adaptation rather than as a phenomenon of 

 phylogenetic importance. 



A. The sensory system is composed of the entire surface por- 

 tion of the brain, i.e., those parts underlying the surface of the 

 prostomium. The forepart of the brain is subdivided into fourteen 

 to sixteen slender lobes of sensory cellular and inside fibrilar tracts. 

 The sensory cellular tracts are not confined to the lobes in front, 

 but extend all over the brain and give off fibers which connect with 

 the subcuticular sense cells or go directly to the cuticle as sense 

 fibers. 



B. The main or cross-connective part of the brain consists prin- 

 cipally of "punkt-substanz" with dorsal sense cells. 



C. Eyes are four in number, the central pair being degenerate 

 close to the surface of the prostomium, and lacking in lense struc- 

 ture. The lateral pair are well-developed but buried deeply in the 

 prostomium and so inverted that the lens is inside and the pigment 

 outside. Neither pair of eyes can be regarded as functional in the 

 adult. 



D. The circum-oesophageal connectives branch on each side into 

 a dorsal and ventral ramus. This is analagous to the phenomenon 

 found in Nepthys where the ocular and the surface sensory parts 

 of the brain are separate structures. 



E. The nuchal ganglia, extending to the rear from the dorsal 

 part of the main brain are connected with a more or less rudimen- 

 tary organ which is doubtfully a functional otocyst. 



F. The suboesophageal ganglion and nerve cord are of the usual 

 annelid form. 



G. There is one segmental nerve extending around the body to 

 a small pedal ganglion, whence it branches into two nerves, a pedal 

 and a dorsal. The former gives rise to a motor notopodial branch 

 and a sensory neuropodal branch. The latter is both motor and 

 sensory in its distribution. 



H. The visceral system consists of a labial, maxillary and a 

 superpharyngeal system. 



(a) The labial system is degenerate from the much more com- 

 plex system in Euuice, or even in the much more closely related 

 Lumhriconereis. It consists of a pair of small short nerves running 



