Biological Papers. 



113 



that for reasons of personal safety such excursions are undertaken 

 mainly after nightfall. If the statements concerning the wander- 

 ings of the males are correct, the period of gestation is short, for 

 the young are nearly all born, in this locality, in March and April. 

 It seems more probable, however, that mating takes place in late 

 fall as well as in early spring; perhaps also during milder periods 

 of the winter, as fairly well-developed embryos are found in the 

 uteri from January to May. The following table gives the results 

 of some investigations conducted in the spring of 1907 and spring 

 of 1908: 



Number of fe- 

 males examined, 

 and date. 



1907. 



.. Feb. 27 



.. Mar. 15 



Apr. 

 Apr. 



Apr. 



Apr. 

 Apr. 



May 

 May 



1908. 

 . . Jan. 



Feb. 

 Feb. 

 Feb. 



Number of embryos. 



4 Mar. 18 



1 Mar. 19 



2 Mar 25 



2 Mar. 26 



3 Apr. 15 



2 Apr. 22 



2 Apr. 24 







4. 5 



5, 5, 0. 







3, 4 



1. 



3, 4 



4, 4, 5 







4, 4, 4 



5, 5, 



4. 4 

 4, 3 



0, 



3, 0, 0. 0, 



May 13 2, 4, 0, 0. 0. 0, 0, 0, 0. 



7 May 14 



10 May 20 



9 Feb. 10 



4 Feb. 12 



0, 0, 0, 0. 0, 0, 



0, 0, 0. 0, 0, 0. 0, 0. 0, 



0, 4 



5, 0, 0, 



5. 0, 0, 0, 

 0, 0, 



6, 6. 5. 0, 0, 0, 0, 0, 



4, 0, 0, 



Stage of development of embryos, etc. 



No signs of pregnancy. 



1 lot nearly fully developed, the other a little 

 less so. 



1 lot only slightly developed; 1 lot about an 

 inch long, thick as one's finger; 1 female 

 evidently pregnant, but fcEti not distinguish- 

 able; 1 female, no signs of pregnancy. 



Uteri congested, but foeti not distinguishable. 



1 lot size of thumb: 1 lotsizeof peanut kernel. 



1 lot size of peanut kernel; 1 female gave evi- 

 dence of having been suckled. 



1 lot size of pea; 1 lot size of peanut kernel. 



2 lots size of end of thumb; 1 lot size of pea- 

 nut kernel. 



2 lots size of end of one's finger; 1 lot size of 

 peanut kernel. 



Evidence that young had been born. 



2 lots foeti in early stages of development; 1 

 lot size of end of thumb. 



2 lots foeti size of hulled peanut; no foeti dis- 

 tinguishable in other female. 



1 lot size of pea; 1 lot size of hulled peanut. 



1 lot in early stage of development; 1 lot size 

 of end of little finger. 



Young evidently born; milk in glands of fe- 

 males. 



1 lot of foeti size of pea; 2 females showed no 

 signs of pregnancy norof having had young; 

 2 females had milk in glands. 



7 females contained no foeti and gave no evi- 

 dence of suckling young; 1 female had milk 

 in glands; 1 lot of foeti size of pea; 1 lot size 

 of lima bean. 



No trace of foeti or evidence of suckling young. 



Of the 10 females none carried foeti and only 3 

 gave evidence of being suckled. 



1 female showed no signs of pregnancy; 1 lot 



of foeti size of peanut kernel. 

 1 lot of foeti size of pea; 1 female no traces; 2 



females had congested uteri. 



1 lot toeti size of peanut kernel; 2 females no 

 traces; 2 females with congested uteri. 



2 females no traces; 1 female with congested 

 uteri. 



1 lot size of pea; 1 lot size of peanut kernel; 1 

 lot size of end of little finger; 2 females no 

 traces; 4 females with congested uteri. 



1 lot size of pea; 1 female no traces; 2 femalea 

 with congested uteri. 



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