General Discnssio7i 6i 



March to November i or later. Some have assumed that if at outcoming in 

 the spring the collector find several separate size groups around certain means 

 we might have year groups. If however a species breeds from February to 

 December i he might have a variation from 4 months to 14 or 15 months. 

 One needs to know transformation sizes (range, average, mode), transforma- 

 tion periods (average, mode, range), breeding periods and countless other 

 factors to make a decent approach to a presumptive determination of year 

 groups. The following table is therefore provisional, based on what evidence 

 we have, and may be easily assailed or in part controverted but may lead to 

 long continued careful studies by subsequent workers. 



In view of the fact that each of these series of presumptive ages was de- 

 termined from plotting the sizes of each species with no thought of previous 

 plottings for kindred species there are quite close parallels in this table. Still 

 one might ask how Rana sphenocephala might reach 78 mm. at the end of the 

 third year when R. clamitans takes 4 years according to the table? The 

 plotting for one or the other may be wrong or each individualistic. Rana 

 clamitans in the south is small for its species. The south is the optimum for 

 Rana sphenocephala. 



In the same way Viosca has called my attention to the rapid growth of 

 bullfrogs in the south as contrasted to the north. The growth given for Ra7ia 

 catesbeiana is for the north, may be very presumptive and far from the truth 

 for Texan, Louisianan, Georgian and North Carolinian frogs. Bullfrogs I 

 have found breeding in February at San Antonio, Texas, but in Ithaca, N. Y. 

 never until June or July. The Rana catesbeiana figures in some ways do not 

 strictly belong in this table. (Table 21) 



In Table 2 1 we have underscored the year each is held to breed. From this 

 we discover that Pseudacris ocularis, Pseudacris nigrita probably, and AcjHs 

 grylhis breed at i year old. These are the small tree frogs. Then comes the 

 oak toad (Bufo quercicus) and narrow-mouthed toads {Gastrophryne carolin- 

 ensis) breeding at 2 years of age. In the tree frogs four species {Hyla femor- 

 alis, Hyla squirella, Hyla andersonii, Hyla versicolor) apparently fall in the 

 two year old class, and three frogs (Rana virgatipes, R. sphenocephala and 

 Rana septentrionalis) also breed two years after transformation. This gives 

 representatives of four families, nine species in all, or about one-half of the 

 table maturing in 2 years or thereabouts. Two tree frogs ( Hyla cinerea and 

 Hyla gratiosa) breed as 3 year olds, and five frogs {Rana clamitans, Rana 

 aesopus, Rana heckscheri, Rana grylio, and Rana catesbeiana) fall in the same 

 class. The last group is one of the most precocious groups of early transfor- 

 mation, namely the southern toad and solitary spade-foot. They transform 

 quickly at small sizes, but have to grow apparently for 4 years before breeding. 



In interpretation of age groups more chance for personal equation comes 

 in the early sizes. For example from transformation onward some would 

 make the frogs grow much faster the first year or so. Some no doubt would 

 merge my first year and second year group into one (namely yearhngs). 

 Herein is one of the crucial periods needing more study. 



