210 NEOMENIA VERRILLI. 



are strongly enlarged, and are united by two commissures of considerably larger 

 size than those in a more posterior position. 



With the exception of the most anterior, the connectives uniting the lateral 

 and ventral ganglia are spaced at fairly definite intervals. The exception arises 

 on each side from what appears to be the connective to the ventral ganglion 

 since no nerve cells occur in its vicinity, and on the other hand it unites with 

 the anterior swollen extremity of the lateral cords. The last named enlarge- 

 ment gives rise to two strong branches of which the smaller, directed anteriorly, 

 makes its way into the vicinity of the bases of the cirri. The other makes its 

 way ventrally and is distributed in part to the somatic muscles, while a com- 

 paratively large nerve extends between the lobules of the anterior pedal gland 

 where it becomes lost to view. Another nerve destined to the same organ arises 

 from the lateral cords about midway between the first and second latero-ventral 

 connectives. 



As usual nerves spring from the dorsal side of the lateral ganglia, and 

 though clearly defined and of relatively large size none have been traced as 

 far as the mid-dorsal hne. They branch repeatedly over the internal face of 

 the somatic muscles which they probably innervate together with the overlying 

 hypodermis. 



The labiobuccal connectives are so closely associated with the lateral for 

 a short distance beyond the brain that though they are fairly distinct they 

 nevertheless occupy the same sheath. Beyond this point they may be fol- 

 lowed with unusual clearness, and owing to this fact more than ordinary care 

 has been exercised in determining the relation of the principal elements. Loosely 

 attached to the muscular coat of the digestive tract each connective extends 

 posteriorly to the labiobuccal ganglion placed about opposite the posterior 

 end of the outlet of the anterior pedal gland. At approximately two thirds of 

 its length from the brain two or three branches are developed of which the 

 largest, crossing the dorsal surface of the pharynx, forms a cominissure. The 

 others, imbedded in the muscular pharyngeal walls, have been followed to a 

 greater or less extent until their subdivisions become so small in cross sections 

 that they disappear from view. At many points minute nerves appear in the 

 pharyngeal wall, and give the impression that they are parts of an extensive 

 plexus such as is known to ensheath the digestive tract in several other molluscs. 

 Other nerves of this same character occur at a short distance anterior to the 

 labiobuccal ganglia. 



Immediately in front of the ganglia a simple, ventral commissure occurs. 



