136 A. J. CARLSON. 



The anterior of these two nerves supplies the reproductive organs. 

 The other nerve runs towards the gill, where it bifurcates, one 

 branch entering the gill ; the other " appears to end in the pericar- 

 dium near the origin of the auricle." In his recent monograph of 

 the Aplysidae Mazzarelli (1893) describes and figures three nerves 

 from the left side of the visceral (called by him deutovisceral) 

 ganglion. Of these nerves the one given off furthest posterior 

 " manda un sotil ramo alia membrana viscerale " (p. 108) ; but 

 no reference is made to the innervation of the heart. Pelseneer 

 (1893) has described the nervous system of Biilla striata and 

 Pleurobrancluea mckdi. In Bulla he dot not figure the periphe- 

 ral nerves from the two visceral ganglia (called by him supra- 

 intestinal and abdominal ganglia), and consequently not the 

 innervation of the viscera and the heart. In PlciirobranclicTa he 

 describes two nerves from the visceral ganglion. The one on 

 the right side passes to the gill. The left nerve is called the 

 genital nerve and the small ganglion on its course the genital 

 ganglion, but the nerves peripheral to this ganglion are not 

 described and consequently not the cardiac innervation. The 

 most recent observations in this field have been make by Bot- 

 tazzi and Enriques on Aplysia (1901). These authors describe 

 a nerve from the right side of visceral ganglion to the aorta and 

 from the left side of the ganglion " un nerf cardiaque, qui donne 

 un rameau au nephredion et un qui va an second estomac tri- 

 turateur (?) " (p. 122). 



The presence of ganglion cells in the heart of Aplysia has been 

 affirmed by Dogiel (1877) and denied by Ranson (1884). 



My own work was done on Aplysia calif ornica, Bnlla globosa 

 and Pleitrobranchcea calif ornica. In Aplysia (PI. VI., Fig. 1 1) the 

 pleural or pallial ganglia of the cesophageal complex give rise to 

 two stout nerves, the pleuro-visceral commissures, which run free 

 in the body cavity of the neck to enter into connection with the 

 large visceral ganglion situated in the body cavity anterior to the 

 visceral mass. From the right and posterior side of this ganglion 

 proceeds a stout nerve (i) which enters the osphradiurn and the 

 roof of the gill chamber. The left and anterior side of the ganglion 

 gives rise to three nerves. The most anterior one (5) enters the 

 mantel and the dorsum of the anal region. The middle nerve 



