PHYSIOLOGY OF THE INVERTEBRATE HEART. 143 



mantle nerve and takes a course lateral to it. On reaching the 

 anterior or cephalic artery the nerve bifurcates, the smaller branch 

 (4) continuing posteriorly to the genital organs. The final desti- 

 nation of this nerve was not determined, but it does not come 

 into relation with the heart. The main branch follows the artery, 

 ventral to it, in a median direction, and at the level of the for- 

 ward loop of the intestine it bifurcates, the smaller branch pass- 

 ing dorsal to the gut, its branches ramifying in the visceral en- 

 velop and on the surface of the liver. None of its tiny rami can 

 be traced to the region of the paricardium and the heart. At 

 the place of bifurcation is usually a small ganglionic swelling (5). 

 The main branch continues posteriorly along and ventral to the 

 artery and can be followed on to the junction of the aortic sinus 

 with the ventricle. Branches from this nerve pass to the main 

 arteries and probably follow them peripherally just as in Plcuro- 

 brancJuza. In large specimens the branch to the ventriculo-aortic 

 junction (7) can be traced on to the ventricle. This is, there- 

 fore, one of the cardiac nerves. The heart is thus supplied with 

 nerve-fibers from nerve 3 and in all probability also from nerve 

 2 (and i ?) just like the two foregoing Dorididae, in both of which 

 nerves enter the heart at the aortic as well as at the auricular ends. 



7. The Pulmonates. - - Ransom (1884) has described nerves to 

 the auricle and the ventricle of Helix: 



" From the median protuberance on the cesophageal gang- 

 lionic mass comes off almost from the middle line a couple of 

 visceral nerves. The larger of the two, the left nerve, runs along 

 the aorta towards the ovisperm duct, to which it gives off a branch. 

 It then divides, and one part follows the aorta into the ventricle 

 while the other goes to the kidney, where it ramifies and some 

 branches are continued to the origin of the auricle " (p. 327). 



Curiously enough, Ransom figures the ventricle as being situ- 

 ated anterior to the auricle. Plate (1898) describes four nerves 

 from the visceral (pleural) ganglion in the Janellidae. Of these 

 nerves three enter the pallial complex and the fourth supplies the 

 renal organ. " Er versorgt in erster Linie die Niere. Ob er, aus- 

 serdem, wie wahrscheinlich 1st, den Herzbeutel und das Herz, 

 villeicht auch die Athmroren innerviert, bleibt weitern Unter- 

 suchungen zu Feststellung vorbehalten " (p. 256). 



