Camels, dromedaries and cats have the end of the penis bent backward (this explains the tom-cat's manner of urination), the tip does not straighten itself or point forward save in erection. Not only the prong but the sheath of rodents points backward and ends near the anus, and in front of it. The penis is slender in ruminants, and in wild boar; thick and round in solipedes, elephant, lamentin (sea-cow, manatee); thick and conic in the dolphin, cylindrical in rodents and primates. The gland, which takes all intermediary forms between ball and point, has in the rhinoceros the shape of a gross fleur-de-lys. In the cats small spikes rise and point toward the base, and in agouti and gerboa there are holding flanges which grip the organs of the female. The prong of many mammifers, a real member, is held up by an interior bone, formed at the cost of the conjunctive partition which separates the two hollow chambers. This penial bone is found in many quadrumanes, chimpanzees, orang-outangs, most carnivora, dogs, wolves, felines, martin, otter, badger, among rodents, beaver, seal, and cetaceous animals; it is lacking in ruminants, pachyderms, insectivora, toothless animals. In man one sometimes finds a trace of it in the form of a slender prismatic cartilage. In the enormous penis of the whale it resembles a bell-clapper. The penial bone diminishes the erectile capacity of the prong in stopping the development of the hollow chambers, but it assures the rigidity of the member, obtained in the other penial type by the inflow of blood which causes the swelling. Man ought to have the penial bone; he has lost it in the course of ages, and this is doubtless fortunate, for a permanent rigidity, or one too easily obtained would have increased, to madness, the salacity of his species. It is perhaps for this reason that great apes are rare, although they are strong and agile. This view would be confirmed if the penial cartilage were found regularly in very lustful men or with a certain frequency among human races most addicted to eroticism.