SENSORY ADAPTATIONS OF BATS. l6l 



men of the uterus and remain alive but inactive throughout the 

 winter. Ovulation and fertilization take place at the return to 

 active life in the spring and development begins at once and con- 

 tinues without a resting stage. Duval ('95) states that bats 

 copulate a second time immediately after hibernation, but RoUinat 

 and Trouessart ('96, p. 220) consider his observations to be 

 erroneous. 



The reproduction of American bats has not been studied in 

 detail. I found Myotis lucifugns copulating in Shawnee Cave on 

 October 27, 1906, and at two unrecorded dates shortly afterward. 

 In Truitt's cave I saw a pair copulating on October 19, 1907. 

 Two pairs of Piphtrelbis were apparently copulating in the same 

 cave on November 29, but they were too high to be reached and 

 I could not be certain. A pair of Myotis siibnlatiis appeared to 

 be copulating early in April, 1907, but they also were in a posi- 

 tion where they could not be obtained or be carefully watched. If 

 mating actually took place at this time it may have been the 

 post-hibernal mating mentioned by Duval, as it is extremely 

 improbable that this species would copulate at a very different 

 season from its near relative. 



In sexual congress the female clings to a vertical wall or ledge. 

 The male attaches himself to the posterior part of the body of 

 his mate, and clings to her fur and membranes with his claws, 

 but also rests in part on the interfemoral membrane and body. 

 The posterior portion of his body is flexed forward, pushing aside 

 the interfemoral membrane of the female, so that contact between 

 the genital organs can take place. Coues and Yarrow ('75) state 

 that the red bat [Lasiurus borcalis) copulates during flight, but 

 this statement is so at variance with the facts observed for the 

 other species that it cannot be accepted without further confirma- 

 tion. 



The uterine contents of M. huifugns were not examined to de- 

 termine at what time fertilization takes place. However, embryos 

 were not present in any that have been examined in the caves, 

 including several as late as April 9, and one on April 27. It 

 can be asserted, that in this species, development does not begin 

 until the beginning of the summer activity of the female. After 

 this time the females seldom or never enter the caves and I have 



