C)74 VISCERAL ANATOMY OF THE AUSTRALIAN TORPEDO. [DeC. 2, 



similarity to that of the ventral mesentery of some Teleostei (ex. 

 Salmo) to venous trunks which pass between the intestinal and ventral 

 body walls '. On the whole, and on consideration of the facts 

 referred to in dealing with the Anurous Amphibia, I am disposed to 

 regard the disposition of the great vessels named as the primary agent 

 in originating the absorption under consideration. 



The so-called abdominal pores of the cartilaginous fishes have 

 been shown by Bridge '" to arise in relation either to peritoneal 

 pouches (dv.p., fig. 5) resulting from outward extension^of the peri- 

 toneum, or to cloacal pits (dv.c.) formed by inward extension of the 

 ventral body-wall. In the specimen of Hypnos here figured, the 

 two were in wide communication on the left side, sufficient to pass a 

 crow-quill ; on the right side the base of the peritoneal pouch 

 {cf. fig.) was constricted, whereby it communicated with the cloacal 

 pit by a minute aperture in its dorsal wall. This is of interest, as 

 Bridge's researches have shown the parts in question to be variable 

 specifically and individually to an unexpected degree. 



DESCRIPTION OF PLATE LVII. 



Fig. 1. Hypnos subnigriim, cJ. Greneral disposition of the viscera, as seen 

 ou reflecting the ventral post-pericardiac body-wall. 



One third nat. size. 



2. The same. The alimentary viscera, dorsal mesentery, and testis, as 



seen from the right side. One third nat. size. 



3. The same. The spleen and appendix digitiformis, represented in re- 



lation to the dorsal mesentery (indicated by a black line a, /3). 



Two thirds nat. size. 



4. The same. The Bursa Entiana, together with the head of the small 



(valve-bearing) intestine and the pyloric chamber of the stomach ; 

 laid open from the left side, to show their contained valves. 



Two thirds nat. size. 



5. The same. Peritoneal pouch and cloacal pit of the right side, lateral 



view from within. Nat. size. 



Eeference letters. 



a.m' . Anterior superior mesenteric artery, 

 a.wi". Posterior superior mesenteric artery, 



af. Appendix digitiformis. 



cd. Stomach (cardiac sac). 



c.h. Gall-cyst. 

 cl. Cloaca. 



d.h. Bile-duct. 



d.m. MiUlerian ducts (coalesced ostia of). 



dv.c. Cloacal pit. 



dv.'p. Peritoneal pouch. 



f.m. Mesenteric furrow, 



f.p. Gastric furrow. 



hp. Liver. 



' Cf. Stannius, op. cit. pp. 250, 251. 



2 Journ. Anat. & Phys. vol. xiv. p. 81 (1879). 



