30 OPISTHOBRANCHIATA OF BRAZIL 



pleural ganglia, and equally unmistakable anastomoses occur 

 with a pedal nerve in each case. These relations will be taken 

 up in their order. 



Left pleural nerves. From the outer upper margin of the 

 left pleural ganglion arise two nerves {pi. i, pi. 2) close together, 

 and are closely enmeshed in the capsule of dense connective tissue 

 surrounding the central nervous system. They are both dis- 

 tributed to the muscles of the lateral and dorsal body wall in the 

 immediate vicinity of the ganglion. The second of these nerves 

 is connected by an anastomosing branch with the second pedal 

 nerve of the same side as is seen in the figure. 



Right pleural nerves. From the right pleural ganglion a 

 single, fair sized nerve arises (pi. i) below and in front of the 

 origin of the pleuro-parietal connective. It passes outward and 

 forms an anastomosis with a branch of the second pedal nerve 

 (p.2) of the right side. The double trunk thus formed then 

 breaks up into a number of branches in the peritoneal membranes 

 and in the dorso-lateral wall of the body. 



Buccal ganglia. The buccal ganglia (buc. g) are nearly 

 vertically placed upon the posterior face of the pharyngeal bulb 

 just below the beginning of the esophagus (PI. Ill, fig. 9) and 

 present an anterior slightly concave face in contact with the 

 bulb, and a posterior arched one, turned away from it. These 

 ganglia are plump rounded bodies of an elliptical outline, slightly 

 flattened, and closely united in the median line by a broad and 

 very short commissure. On Plate II the buccal ganglia are shown 

 in their relations with the remainder of the central nervous 

 system; in figures 10 and ii of Plate III they are shown isolated 

 in ventro-posterior and dorso-anterior views respectively. The 

 short strong cerebro-buccal connectives (c. b. con.) unite them 

 to the cerebral ganglia above, being inserted laterally upon the 

 posterior surface, between the bases of the second and third 

 buccal nerves (PI. Ill, figs. 9, 10 and 11), and curving laterally 

 upward to the cerebral ganglia. All the nerves of the buccal 

 ganglia bear small white pigment spots arranged in a single 

 series at regular intervals along their proximal portions. 



Buccal nerves. In the description following the numbering 

 of the nerves follows their order of origin from the anterior end 

 of the ganglia backward, an order followed by Mazzarelli on p. 



