NATURAL HISTORY SOCIETY OF GLASGOW. 179 



the Dolphin, however, it exhibits also a certain slight tendency to 

 transverse folding, and has a more glandular appearance. But the 

 most striking contrast is in the rectum, which, in the Porpoise, is 

 of much the same diameter as the rest of the intestine, and presents 

 a similar smooth surface and longitudinal folds; while in the 

 White-beaked Dolphin it is greatly dilated, with a much-thickened 

 mucous membrane thrown into reticulated irregularities, which 

 seems to shew that digestive and absorptive functions are still 

 remarkably active at the very termination of the intestine. In 

 both animals the narrow part in the grasp of the sphincter is an 

 inch and a half in length, and of slight vascularity. Even in the 

 Porpoise it is to be noted that the calibre of the intestine increases 

 from the stomachic to the rectal end, and the longitudinal rugae, 

 which are disposed on the unattached side, increase in number. 



Heart and great vessels. — The principal points shewn by the 

 specimens were, the shortness of the auriculo-ventricular valves, the 

 remarkable venous plexus surrounding the commencement of the 

 pulmonary artery and falling into the coronary vein, the great 

 strength of the auricular walls, and the upper end of a large rete 

 mirabile on each side, which is continued back under the ribs, in 

 connection with the intercostal arteries; also, the ductus arteriosus, 

 which is minutely pervious, and in reference to which the exhibitor 

 remarked that he had found this vessel still more widely patent 

 in another diving animal, the Seal. 



Lungs. — The density of texture and want of lobation of the lung 

 of the porpoise were pointed out by John Hunter. The specimens 

 exhibited shewed further a sulcus at the apex of the right lung 

 (found also in the Dolphin). In it lay the vena azygos, and thus 

 the projection internal to it represents the supernumerary lobe 

 occasionally found in man. The pleura is prolonged into a remark- 

 able fringe along the costo-diaphragmatic border of the lung. It 

 is thick, and exhibits a system of blood-vessels of its own, which 

 in one specimen has been stripped off with it, and is seen to be 

 independent of the lung 



Male genito-urinary organs. — These are similar in the two 

 species. It was shewn that within two inches of the slender point 

 of the penis, the combined corpora cavernosa suddenly become 

 smaller, and at the same time take an abrupt turn dorsally, as if 

 by loss of substance on the ventral aspect, and become very feeble 

 further forwards, so that the tail-like end of the organ can no doubt 



