228 DORYMENIA PERONEOPSIS. 



though more posteriorly, and following along the walls of the sheath are inserted 

 in the forward border of the cloacal chamber wall. 



Owing to the fact that the sheath surrounding the larger nerve bundles 

 stains with unusual clearness, considerable care has been taken to trace out 

 the more important trunks. The brain, holding the usual position dorsal to 

 the pharynx, is more than usually globular and lacks the customary groove 

 in the region of the commissure connecting the nerve cells of the two sides. 

 From its anterior face the usual three pairs of nerves take their origin, and 

 after connecting immediately with small, spherical ganglia are distributed to 

 other ganglionic masses attached to the external surface of the atrial wall. 



From the sides of the brain the lateral, pedal, and labiobuccal connectives 

 originate as separate, distinct roots. At the point of union of each lateral 

 connective with the ganglion there is a well-defined enlargement which ante- 

 riorly gives rise to a strong fibre passing forward and closely applied to the 

 somatic musculature. In the neighborhood of the atrium and atrial ridges 

 it branches repeatedly and the resulting subdivisions give evidence, in some 

 instances at least, of uniting with ganglia in the neighborhood of the cirri. 

 From this same anterior enlargement a small nerve arises and passing ventrally 

 becomes lost in the region of the outlet of the anterior pedal gland. The anterior 

 end of each pedal ganglion is likewise developed into a globular enlargement 

 from which one or two nerves arise that soon become lost in the surrounding 

 muscle tissue. It may be mentioned that the lateral and pedal connectives are 

 each united by a small connective in close proximity to the brain. 



The labiobuccal ganglia are ellipsoidal bodies occupying a space between 

 the muscles of the radula and the lateral portions of the overhanging stomach- 

 intestine. There is developed, from the anterior surface of each, a strong nerve, 

 the labiobuccal connective, which in the contracted state of the present speci- 

 men is considerably twisted throughout its course to the brain. About one 

 fourth of the distance from the ganglion to the brain each of these connectives 

 enlarges considerably, though apparently without the presence of gangUon 

 cells, and gives rise to three distinct nerves. One of these pursues a course 

 anteriorly, and imbedded in the muscles of the gut unites with a corresponding 

 branch from the opposite side, thus forming a comnaissure. Throughout its 

 course at least three pairs of small nerves are developed which often branch 

 repeatedly before being lost to view in the surrounding muscles. The other 

 two nerves springing from the labiobuccal connective pass ventrally where 

 one becomes lost when lateral to the outlet of the ventral salivary gland. The 



