PHYSIOLOGY OF THE INVERTUBRATE HEART. 149 



and anastomoses extensively on its course along the vena cava 

 and sends numerous branches to the renal veins. In Loligo 

 Cheron figures a nerve as passing to the auricles from either 

 visceral nerve at the level of the commissure in a manner similar 

 to that in Octopus. In Ommastrephes there is no distinct gang- 

 lionic enlargement at the junctions of the commissure with the 

 visceral nerves. The nerve passing to the heart takes its origin 

 from the commissure and not from the visceral nerves directly, 

 and this nerve enters the ventricle, not the auricle. 



At the level of the auBicles each visceral nerve bifurcates, the 

 smaller branch of each (3, 4) taking a median direction on the 

 ventral and posterior surface of the systemic ventricle. Near the 

 origin of the posterior artery these branches are connected by a 

 tiny commissure, after which they unite into one nerve-trunk (10). 

 This follows the posterior aorta for a little distance to finally 

 enter the reproductive organs. There is a slight ganglionic 

 enlargement at the place of bifurcation. 



The branches to the gill ventricles and the auricles (5) leave 

 the visceral nerves close together a little distance before these 

 nerves enter the gills. The nerve to the gill heart (6) runs pos- 

 teriorly along afferent gill sinus and penetrates the substance of 

 the gill heart at its junction with this sinus. The auricular nerves 

 are very slender. In some specimens they are given off, not 

 from the visceral nerves directly, but from the branch to the gill 

 ventricles. There is a distinct ganglionic enlargement on the 

 visceral nerves at the point of origin of the nerves to the gill 

 ventricles. 



This ventral visceral nervous complex is connected with the 

 cerebro-gastric nervous system by a commissure (8) from the 

 left visceral nerve to the gastric ganglion (".). This nervous 

 connection has not, to my knowledge, been noted before in the 

 cephalopods. I was unable to make it out with a certainty in 

 Loligo owing to the difficulty of distinguishing between the 

 smaller arteries and the finer nerve-branches. 



The systemic heart of Oinuiastreplies (and in all probability 

 also Loligo] is thus furnished with a double nervous supply 

 similar to that of the gasteropod molluscs, fibers from the visceral 

 nervous complex entering the systemic heart both at the auricular 



