268 yORDAX. [Vol. V. 



cases. During this period the animals remain on the floor of 

 the aquarium in almost exactly the same spot, and the male is 

 not, as incorrectly stated by most observers, "jerking the female 

 unmercifully around during the whole time." On the contrary, 

 both animals are well-nigh motionless, with the exception of 

 the often-described fanning movement of the tail of the male. 

 This half-stroking, half-fanning motion is kept up with more or 

 less rhythmical regularity, first on one side and then on the 

 other, and probably serves to excite both animals, although 

 heretofore it has been not unnaturally regarded by many 

 observers as for the purpose of diffusing the spermatozoa 

 throughout the water. The female responds by slowly raising 

 her tail until it forms an angle of 45 , or even a right angle, with 

 her body, and occasionally repeats in her turn the slow fanning 

 movement. 



From this condition the male passes gradually into a more 

 violent stage, which has been wrongly stated by some writers 

 to extend over the whole of the foregoing period. This more 

 violent stage usually lasts for only about ten minutes, and dur- 

 ing this time the unhappy female is dragged, jerked, and pulled 

 over the whole floor of the aquarium, the entire body of the 

 male meanwhile quivering with intense excitement. The cloaca 

 of the male at the same time begins to swell and to show a few 

 whitish papillae projecting from the sides. At the climax of 

 his agitation the male, after a few rapid bendings of his body 

 from side to side, leaves the female, and with his tail slightly 

 raised, his cloaca widely distended with numerous white pro- 

 truding papillae, throws his whole body into a series of rapid 

 and strenuous undulations, and waits for the female to follow 

 him. If she does this and presses her head lightly against his 

 tail 'and cloacal region, the male soon deposits a spermatophore 

 and then creeps on to a distance of a few centimeters, where, 

 if the female still continues to follow him, he soon deposits 

 another. I have often seen one male discharge as many as 

 three spermatophores in this way, but have never seen one 

 individual discharge at one time more than this number. 



The spermatophore consists, broadly speaking, of three parts : 

 a thick, irregular gelatinous mass about six millimeters in 

 diameter which adheres to the bottom of the aquarium ; a tough 

 elastic spine projecting upwards from this base; and, borne on 



