ADAPTATIONS AND DISTRIBUTION 



comes rigid and swollen wilh eggs and thus has greater girth or lirinness. 

 The female is supposed to be released by the male's sensing a greater flabbi- 

 ness or a lesser girth after eggs are laid. This may well apply to some ranas, 

 as Noble and Ferris have shown, although I do not see how the increase in 

 jelly about the ovulated eggs in the uterus (Noble and Aronson, 1942) can 

 be a factor, since there is no such jelly in any significant amount until the 

 secretion of the oviduct swells to form it after the eggs are laid. Also, it ovu- 

 lation occurs only after clasping in these species (as I have thought probable) 

 then there are no eggs in the uterus when the male clasps. 



Females and juveniles of both sexes of B. cognatus, B. conipactilis, B. t. 

 amerlcanus , B. insidior, B. w. jotvleii, and B. w. woodhousii, when picked up 

 by an observer, and often when clasped by a sexually excited male of any 

 species, typically take large quantities of air into the lungs and sometimes 

 become so rigid and rounded that a common three-celled flash light may 

 be sufficient illumination to see the outline of the viscera through the skin 

 of small to medium-sized individuals. This is primarily a protective mecha- 

 nism. I am not certain whether this rigidity is retained during normal egg 

 laying; but I am certain that it is by females which have laid their eggs and 

 are subsequently clasped. Under these conditions, I cannot believe that rigid- 

 ity or girth of the female's body has any but the most minor effect on sex 

 recognition in these toads. 



In Hyla v. versicolor, the male also "protests" when clasped or trodden 

 upon during breeding activities, but the male of Microhyla c. olivaceci appar- 

 ently does not. (However, I have had only limited opportunity to observe the 

 latter at this stage). I have also failed to note a warning croak in the female 

 of Rana berhmdieri such as described for R. pipiens by Noble and Aronson 

 (1942). This, plus the many other detailed differences in breeding habits in 

 these two frogs already reported above (see also Bragg, 1941, 1941b, 1941d,) 

 makes it at least possible that the mechanism of sex recognition is somewhat 

 different in these two closely related forms. 



In Scaphiopus, voice appears to be the principal factor, at least in S. hom- 

 bijrons, S. hammondii, S. couchii, and S. hurterii (Bragg, 1945). My obser- 

 vations on the remainder of the Oklahoma species of Salientia are incon- 

 clusive on this point. 



(4) Production and BcrtiUzation of Eggs. 



My observations have shown less about this phase of reproduction than 

 about any other, but the following should at least be noted: (a) Individuals 

 of some species take a much longer time for egg-laying than others. Thus, 

 Bufo cognatus commonly requires from ten to twelve hours and Pscudacris 

 darken, six to eight; whereas Microhyla c. olivacea, Rana berlandieri, Hyla 

 V. versicolor, and all species of Scaphiopus in Oklahoma require much less 

 time, whether in a pool or in the laboratory, (b) Some species produce all of 

 the eggs of a clutch at one time and place; others lay a few eggs here, some 

 more there, scattered about in a pool. To the first group belong all of the 



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