General Discussion 33 



THE EGGS 

 (Pis. VI, VII, VII, IX; Text Fig. i) 



Incorporated with this consideration of our southeastern species is a 

 previous key to the eggs of our northeastern forms. The combination may be 

 termed "A key to the eggs of the Sahentia east of the Mississippi River." 



Workers will discover the following species missing from the key because 

 the authors themselves have had no opportunity to secure both fresh and 

 preserved materials of these species: 



Hyla andersonii — Eggs first found by T. Barbour and later by G. K. 



and R. C. Noble. 

 Hyla c. evittata — Eggs found by M. K. Brady. Quite similar to H. cinerea. 

 Pseudacris ornata — Eggs not known. Described by J. K. Strecker. 

 Pseudacris nigrita — Eggs most certainly like Pseudacris triseriata, P. 



feriarum, and P. septentrionalis. 

 Rana areolata— Eggs described by H. P. Wright and G. S. Myers. 

 Rana cantabrigensis — Eggs very similar to R. sylvatica. 



The season of breeding for species in the north is marked both at the 

 beginning and at the end. Each species occupies four or five weeks except 

 Bufo americanus and Rana clamitans. The exceptions may require two or 

 three months for ovulation. In the southeastern states when once a species 

 has begun, its season of breeding may extend throughout the summer or 

 even into the early fall, dependent upon the high crests of precipitation. 

 These species, although of a swampy region, wait for the rains and in this 

 reliance on precipitation they suggest our desert species of Texas and Arizona. 

 Those which do not begin until June have at least eight to ten weeks of 

 ovulation. This minimum period for a species of the south is the maximum 

 period for a northern form. Species such as Rana sphenocephala, Bufo ter- 

 restris and Acris gryllus, which begin early in the season, breed during 25-30 

 weeks of the year, if not longer or from February to September or October. 



The number of eggs in a complement may vary from 100 in the smallest 

 species, Pseudacris ocularis, to 20,000 in Rana catesbeiana, the largest form. 

 The range in the tree frogs (Hylidae) is from 100 (Pseudacris ocularis) to 

 2,084 (Hyla gratiosa); in the toads (Bufonidae) from 610 (Bufo quercicus) 

 to 8,000 (Bufo americanus); in the frogs (Ranidae) from 349 (Rana virgatipes) 

 to 20,000 (Rana catesbeiana). The complements of the narrow-mouthed toad 

 Gastrophryne carolinensis) and the spade-foot (Scaphiopus holbrookii) are, 

 respectively, 869 and 2,332. 



The eggs of seven species, Hyla cinerea, H. femoralis, H. versicolor, Rana 

 catesbeiana, R. clamitans, R. grylio and Gastrophryne carolinensis float on the 

 surface of the water; the eggs of the other 17 species are submerged. In 

 northern or southeastern states no form with buoyant eggs lays before May 

 10. The II or 12 early breeders have submerged eggs. These are usually 

 with firm jelly envelopes except for Pseudacris triseriata and Scaphiopus hol- 

 brookii, which have the consistency intermediate between the firm jellies of 

 early breeders and the loose surface films of late breeders. One form. Gas- 



