Zool— Vol. I.] RITTER—DIEMYCTYLUS TOROSUS. 95 



certainty all the details of the method of fertilization, I still 

 believe that the sperm by some means reaches and enters the 

 cloaca of the female during the act of copulation. I would 

 not, however, be understood to mean by copulation that an 

 actual uniting of the external reproductive parts of the two 

 sexes is an essential element in it. I simply mean by it the 

 grasping and holding of the female by the male. My 

 reasons for believing this are chiefly two : First, although 

 nothing is more common during the breeding season than 

 to find the females held in the grasp of the males, I have 

 watched for a great deal, but have never seen a suggestion 

 of such processes as are gone through in several other spe- 

 cies; e. g., in Axolotl (Gasco '81 and Zeller '90), Triton 

 (Gasco '80, Zeller '90 and '91), or D. viridescens (Jordan 

 '91 and Gage '91 ) . In all these cases fertilization consists in 

 a preliminary love-making, during which the male discharges 

 one or more spermatophores, not while he holds the female 

 in his embrace (in Axolotl this phase of the proceeding is 

 apparently omitted entirely), but free upon the floor of the 

 aquarium, where it is afterwards picked up by the cloaca of 

 the female. My second reason for believing fertilization to 

 be more direct than this in our species is the fact that I have 

 captured one copulating pair in which a large quantity of 

 sperm was contained in and protruding from the cloaca of 

 the female. This case might seem to be conclusive on the 

 point, though of course it is not wholly so, for in the first 

 place the actual passage of the sperm mass from the male 

 to the female was not observed, and in the second place it 

 is quite conceivable that this passage may have taken place 

 by some means less direct than that supposed; or again it is 

 by no means impossible that the sperm mass might have 

 been obtained by the female from some other male than the 

 one with which she was found mating. But, on the whole, 

 when all the facts observed are considered, it seems to me 

 that the belief above expressed is warranted, 



The lips of the male cloaca become enormously tumid 

 and enlarged at the height of sexual activity (fig. 2), and 

 during copulation these are made to straddle the dorsum of 



