The frog book; North American toads and frogs, with a study of the habits and life histories of those of the northeastern states. / With over three hundred photographs from life by the author. By Mary Cynthia Dicker
The Batrachian has two occipital cou=_dyles, except in the case of some Stegocephali. The Batrachian is characterized by the presence of a // jfenestra ovalis and stapes ancQii internal nares. " I When the eggs are first laid, part of this yolk can be seen occupying the lower portion of the egg under the more or less pigmented upper portion. (Fig. 202 .) The dark pigmented portion of the egg at the top (later the whole surface becomes black or brown in colour) allows a greater absorption of the
... r absorption of the sun's heat than would a lighter colour. So the develop-3 The lachrymal canal shifts upward and backward toward the eye and enters the lower eyelid. (Fig. 287 .) The horny parts of the mouth are dropped and the mouth cavity increases in size. The tail becomes smaller by absorption from within. The tadpole takes on habits of rushing to the surface or of resting wholly out of the water (Figs. 287 and 288), showing that the lungs, which for some time before had been functional in company with the gills, now take on all of the respiratory work (except 5 c. Vertebra procoelous, ribs absent, teeth absent. Family 3 Bufonidce (Toads), pp. 44 and 63. 2. Terminal phalanges of skeleton claw-shaped and supporting adhesive disks. a. Vertebrae procoelous, ribs absent, teeth on upper jaw. Family 4. Hylidce (Tree Frogs), pp. 46 and 117. B. Sacral diapophyses cylindrical. (Fig. 6.) Vertebrae procoelous, ribs absent teeth on upper jaw. (Very like the frogs, except for the arciferous shouldergirdle.) Family 5. Cysitgnathidi^(Lithodytes, etc., pp. 45 and 163). 7 Of the North American species, ten are members of the genus Hyla; the others belong to Acris, Chorophilus, and Smilisca. (Refer to p. 117.) Family V. CysHgnaihidoe-The old family of the Cystignathidas is nearly as large as the Hyhdae. It is not well defined, but overlaps in its characteristics 9 the Urodela and Salientia arose separately from the Stegocephali or whether they had intermediate common ancestors. The oldest form of the Salientia known is represented by fossils from the Jurassic beds of the Rocky Mountains^(representin g the middle .periods (3f._tb-£-Age_jof R pptiles) , -So little is known of this form, however, that it has little weight. The_garHest relia ble evidencê f anything approaching modern types is^iven by a small skeie-_ ton" found in the Cretaceous_of_Beigium (the latest peno3 of the Reptilian Age, just previous to the Tertiary); this is thought to of the heart do not fall much below freezing-point, the frozen parts will recover. Since sleep is induced in specimens at varying temperatures below 10°C , it is easy to understand why Batrachians are not found in the extreme north. IS Vocal bladders inflated from the middle of the base of the throat are to be found in Bufo cognatus, Bujo compaclilis, and Bujo quercicus.^ (Fig. 8. ) Vocal pouches visible at the shoulder arê Living male specimens of Bujo hemiophrys and Bufo debilis have not been examined. 19 During spring and early summer we are likely to hear not the voice of a single performer of a given species, but the complex sounds produced by a chorus of performers. The result of the many voices may be a harsh and discordant medley or an effect of harmony, depending on the species, the number singing and the vigor and rapidity with which they are producing the sounds. Rana cateshiana and a few others do not sing in chorus. The females, as a rule, produce less loud and emphatic calls than those given by the males. They never show external vocal pouches. In some cases they seem to be voiceless. However, many that were thought voiceless have, during later investiga-21 Absence or presence of moisture, other conditions being equal, seems also to play a part in causing the pigment cells to contract or expand. Toads kept in a dry * Blind specimens change colour much less rapidly than do those that are normal. 23 the attacks of an enemy like the snake that expected to swallow it whole and head first.