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The leptodactylid toads of the genus Elcuthcrodactylus are unusual among anurans in that they lay large-yolked, unpigmented, terrestrial eggs and have no aquatic larval stage. The embryology of one member of this group, the Jamaican species E. nubicola, has been described in some detail (Lynn, 1942) and it was Lynn, W Gardner. 1948. "THE EFFECTS OF THIOUREA AND PHENYLTHIOUREA UPON THE DEVELOPMENT OF ELEUTHERODACTYLUS RICORDII." The Biological bulletin 94, 1-15.

As a result of the early work of Bohr and Hasselbalch and the later experiments of Murray and others there is available a considerable body of information concerning the respiratory exchange of the chick throughout its embryonic life and, although vertebrate groups other than birds have been less extensively investigated, the respiratory characteristics of the embryos of various fishes and amphibians are also fairly well known. Only two investigations of the respiration of reptilian embryos have been reported however, and these deal with but a few stages.Bohr (1904) carried on some experiments with the eggs of the snake, Coluber initi'i.r, and found a decrease in respiration intensity with increasing age. The respiratory quotient as determined by Bohr was about 0.9 at all of the stages studied.Zarrow and Pomerat (1937) studied four eggs of the Green Snake (Liopcltis z'crnalis) which were in late stages of development and also investigated the respiration of the young after hatching. They report that the absolute gas exchange of the eggs was of the same order of magnitude as that of the young snakes but the respiratory quotient of the hatched animals was significantly greater than that of the embryos.