GROWTH KATl-.S AND SICXL'AL MATURITY 



comparable to that of some adults at least a year and probably two years 

 older. These results were confirmed at a later date (June 21) when calling 

 males 75 mm. in length and with fully formed tunctional vocal pouches were 

 collected from breeding congresses at the same time that other males of this 

 size and with incompletely developed pouches remained away from the 

 breeding pools. 



The year 1939 was a poor breeding year for B. cognatus. Rains were late 

 and most egg-laying was in June. For this reason pools evaporated, killing 

 all tadpoles. Despite constant search, we found evidence of the emergence of 

 only ten young toads from a single pool in the Norman region. It was thus 

 not possible to follow the young toads of the 1938 season into their third year. 

 After a light shower on May 20, 1940, twenty-two toads were collected 

 and measured. Of these, six were judged to be of the 1938 brood, two were 

 t]uestionable, and the remainder were judged to be older. The next night, 

 after a heavy shower in the late afternoon, twelve calling males were selected 

 from a breeding congress because they seemed to be the smallest of hundreds 

 in the pool. These ranged from 66 to 78 mm. in length. Only two males of 

 this approximate size could be found on an adjacent roadway (62 and 64 mm. 

 respectively). Both had immature vocal pouches. 



Observations were discontinued shortly after this until September. The 

 fall was dry, however, and no further information was secured until the 

 following spring. It should be mentioned that very large breeding congresses 

 were seen in early July by Dr. Charles C. Smith and that these are known 

 to have been successful in the production of young metamorphosed toads. It 

 is also practically certain that eggs laid in May produced young toads. 



In the spring of 1941, therefore, young toads of two ages were to be 

 expected in our collections, as well as young adults of the 1938 season. On 

 April 14 and 27 fifteen individuals, obviously of the 1940 season, were taken. 

 They ranged from 44 to 75 min. in length, four of them certainly being males. 

 One 55 mm. individual, probably froin a late summer brood, chirped when 

 picked up and was, therefore, classified as a male although no sign of the 

 vocal pouch was present. Other toads collected at the same time were thought 

 to be of the 1938 season, but they could not be distinguished with certainty 

 from older individuals. 



The spring of 1941 (April through June) was the wettest in many years, 

 and B. cognatus responded by producing millions of young (Bragg, 1942). 

 Accordingly, we had the best opportunity for observations on growth rates 

 yet afforded. 



So long as the young metamorphosed toads remained diurnal, we could 

 collect them in numbers about the pools; but after they became nocturnal 

 we were forced to make collections at night at what seemed to be the most 

 favorable times. Accordingly, as the weather became hotter and drier, our 

 data became more scattered and meager, but we succeeded in tracing their 

 growth fairly well until they hibernated for the winter in late October. 



Collections were made in several areas during late spring and early 

 summer, but it soon became evident that we were dealing with several age 



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