86 The Bullfrog, Rana catesheiana Shaw. 



were tadpoles which would requh-e two weeks more before transforma- 

 tion. In 1912, we found several transforming August 26, and a few 

 tadpoles looked as if they might transform in October, November, or 

 the next season. 



The mature tadpoles in early summer begin to come out in the 

 shallow water. Here they hide in the Chara, Nitella, Myriophyllum, 

 Ceratophyllum, etc., or they rest beneath the lily-pads (Castalia and 

 Nuphar) , pond- weeds (Potamogeton) , and other surface plants. Another 

 favorite place of transformation is among pickerel- weed (Pontederia) , 

 arrow-head {Sagittaria), and water-plantain {Alisma), which afford 

 an overhead cover. Occasionally, around ponds where shallows are 

 absent, stumps — of trees and fallen logs — and trees fringe the edge and 

 their roots extend out into the water. Thereon, we find a favorite 

 transformation-site for the species. At this period they appear to be 

 in hundreds or even thousands. The transformed individuals present 

 a spirited sight as one approaches. They are shy and, long before one 

 gets within range, they start skipping over the vegetation, giving the 

 alarm note so characteristic of the species when surprised. Equally 

 interesting is it when they occupy perches along the stumpy edges of 

 deep ponds. It seems as if a wave of little bullfrogs keeps going before 

 one as he skirts the pond. 



Inasmuch as this species requires two years to mature, we might 

 naturally expect that with varying conditions the tadpoles would be 

 of diverse sizes at transformation, due to inequalities of growth. In 

 none of the eight species under consideration is there such a range of 

 size at transformation as in Rana catesheiana, varying from 43 to 59 mm., 

 a range of 16 mm., the average size of transformed Hyla versicolor, or 

 \\ times as much as the average size of transformed Hyla pickeringii 

 or Bufo leniiginosus americanus, or twice as great as the range in any 

 of the other seven species. A curve of 124 specimens gives 53 mm. as 

 the average, or a mode of 54 mm. (Plate x, Fig. 8.) 



THE AUTUMNAL DISAPPEARANCE. 



This is truly an aquatic form, rarely leaving the water or its vicinity 

 to take long migrations, except when catastrophes befall their ponds 

 (breakings of dams) or breeding sites, when, to adapt themselves to 

 new conditions, they may seek another equally attractive place or 

 occasionally be found in spots not exactly typical for the species. 

 Their active life from egg onward is spent in the water, and there its 

 dormant period is passed. The latest autumnal records we have, are 

 September 22, 1900, and October 14, 1899. In the latter case Mr. 

 T. L. Hankinson found several torpid specimens under stones in our 

 college hydraulic reservoir. 



