GROWTH RATKS AND SEXUAL MATURITY 



Both these notes arc distinctive and immistakable to anyone lamiliar 

 with them. 



8. Sizes of mated lemales in breeding pools at the same time are not similar 



to those of small females on adjacent roadways. Mated females have 

 always been found to be the larger. This seems to indicate that in the 

 females sexual maturity is not attained at this time. We believe this to 

 be the case, but our data, while consistent, are too meager to warrant a 

 clear statement on the matter. 



9. Toads feeding in fields and along roadways late in summer of their third 



year (and in breeding pools the following spring) are practically indis- 

 tinguishable from older individuals, both in sexual development and in 

 size. It is probably true that a selection of the smallest males (and cer- 

 tainly true of females) would contain more of the younger toads than 

 of the older ones but there is no way to pick out individuals of known 

 ages. 

 10. It follows from the above that: (a) most males of B. cognatus in central 

 Oklahoma reach sexual maturity, regardless of the size attained, at the 

 beginning of their third season; some females may do so but most 

 probably do not; (b) most females reach sexual maturity and may breed 

 one year later than their brothers; (c) by the end of their third summer 

 younger toads of neither sex can certainly be distinguished by size from 

 older individuals. 



TABLE I 



Snout to vent length of adult Biijo cognatus in Oklahoma. Range (R) expressed to 

 nearest mm.; arithmetic mean (M) expressed to nearests O.I mm. N ^ Number in each 

 category. 



Preserved Males — Cleveland County 

 Preserved Males — Elsewhere 

 Living Males — Cleveland County 

 Total Males — Cleveland County 

 Total Males 



Preserved Females — Cleveland County 

 Preserved Females — Elsewhere 

 Living Females — Cleveland County 

 Total Females — Cleveland County 

 Total Females 



Lengths of B. cognatus individuals at breeding — all specimens measured (snout-vent) 

 while alive. 



Males — Calling when captured 

 Males — Clasping when captured 

 Males — Total 

 Females — Clasped when captured 



57 



