THE ANATOMY OF A NEW SPECIES OF BATHYDORIS. 197 



gastro-oesophageal ganglia, and the paired gastro-oesophageal nerves (g.o.n.) arise 

 directly from the stomato-gastric ganglia. The paired nerves pass back in the con- 

 nective-tissue investment of the oesophagus to the stomach, where they form a joint 

 ganglionated anastomosis with the gastric branch of the visceral, as already described. 

 From this plexus the stomach and liver receive their innervation, while the salivary 

 glands are supplied from the gastro-cesophageals on their way down the oesophagus. 



This compound system of gastro-hepatic ganglia is paralleled in the Dorids, where 

 it was described by Alder and Hancock, while Dreyer has lately shown that an 

 analogous arrangement is present in Aeolids and Tritonids. 



Like the other species examined anatomically, B. brotvnii showed no trace of organs 

 of sight, and otocysts could not be found by careful surface examination. They were, 

 however, found on staining and clearing and also in sections of the brain. They are 

 two small sacs placed close to the pleuro-pedal connectives on their lower aspect 

 and partially imbedded in the connective -tissue capsule that surrounds the brain. The 

 author has found small otocysts similarly placed in some of the Polyceratidae. Otocysts 

 were not found in the species examined by Bergh and by Eliot. 



The Excretory System. (Fig. 8.) 



The kidney of Bathydoris is unusually well developed. This was also noted by Eliot, 

 who described two fern -like organs lying over the liver as well as the renal syrinx. 

 Eliot, however, misconceived the nature of the renal organ, since he took the paired, 

 fern-like structures to represent the main portion of the kidney, whereas they are 

 merely outgrowths of its floor or ventral wall in the posterior half. The whole renal 

 organ is a huge sac extending from almost the extreme posterior end of the body to 

 within a short distance of the head, but narrowing in front on account of pressure 

 between the alimentary canal and the genital mass. Posteriorly, its delicate dorsal 

 wall is overlain by the pericardium, to which it is connected by fibres. Elsewhere it 

 bulges free except where it is pinched by the intestinal loop (int.). This dorsal wall 

 is throughout non-glandular, except at two points — namely, at its extreme anterior 

 corner (h.g.') and at a place in front of the pericardium (b.g.") where a diverticulum of 

 it lies as a flap across the intestine. These two points will be further mentioned in 

 connection with the vascular system, because the two phagocytic or blood glands lie 

 here adherent to the wall of the kidney. The glandular part of the kidney is therefore 

 almost entirely confined to its ventral wall and to those parts of it which are folded 

 inwards into the renal cavity as the two fern-like structures seen by Eliot. These, 

 however, are not two but six in number, the posterior pair being more fern-like than 

 the other two which lie on the surface of the gonad (h.g.). These glandular regions 

 coincide with the areas of distribution of great branches of the aorta, and the narrow 

 strip-like folds forming the two anterior pairs may easily be mistaken for the arterial 

 trunks themselves, which actually lie within them below the renal wall. The vascular 



