142 A. J. CARLSON. 



of the nerve is continued posteriorly to within a short distance 

 of the large forward loop of the intestine where it bifurcates, the 

 smaller branch (10) passing along the anterior aorta ventral to 

 the intestinal loop, the larger branch ( 1 1 ) turning slightly to the 

 right reaches the base of the auricle and the gill along the 

 rectum on the right side of the pericardial cavity. I could follow 

 the smaller branch (9) along the aorta to within 2 mm. of the 

 ventricle, but not on to the ventricle itself; nor could I trace any 

 branch from the other division of the nerve on to the auricle. 

 Electrical stimulation of the nerve 7 shows that fibers from this 

 nerve reach both auricle and ventricle. The course of this nerve 

 (7) is very similar to that of the "visceral" nerve in Montcrdna 

 (PI. VI., Fig. 14, i'n). The left side of the supracesophageal 

 ganglion gives rise to a small nerve (4) which innervates the 

 stomach, and probably also the digestive glands and the intestine. 



Triopha grandis attains to a considerably greater size than either 

 of the two foregoing Dorididae, but it is much less abundant. I 

 have obtained only a few specimens of this nudibranch at Mon- 

 terey Bay during the months of July and August, when it comes 

 into shallow water to breed. I was therefore unable to make 

 any physiological experiments on the heart and the heart-nerves, 

 but sufficient material was at my disposal to work out the cardiac 

 nerves anatomically. This appears to be essentially the same as 

 that of the previous species, only that the greater size of this 

 mollusc enables one to follow the nerves to their terminations 

 with greater accuracy. Nerves I and 2 (Fig. 16) take their 

 origin on the posterior and lateral sides of the brain and pass 

 laterally and posteriorly on the dorsal surface of the visceral 

 mass close to the visceral envelop, on this course sending numer- 

 ous branches to this envelop and to the dorsum. At the level 

 of the sinous passages from the gill to the auricle the two nerves 

 enter two small ganglia situated in the angle made by the base 

 of the auricle and the rectum (9). These ganglia are joined by 

 a commissure. From each ganglion a tiny nerve passes dorsally 

 and anteriorly evidently entering the pericardium and the auricle. 

 Stouter branches pass posteriorly into the gill. These branches 

 have several small ganglia on their course. 



Nerve 3 takes its origin slightly dorsal to the right branchio- 



