1911 Encyclopædia Britannica/Surinam Toad

SURINAM TOAD (Pipa Americana), an aglossal tailless Batrachian, rendered famous by its mode of reproduction, first observed in 1710 by the Dutch anatomist F. Ruisch. It inhabits South America east of the Andes and north of the Amazons, and is thoroughly aquatic. In its extremely flattened head it is paralleled by two other vertebrates only, which, curiously, inhabit the same parts of South America, viz. the Silurid fish Aspredo batrachus and the Chelonian Chelys matamata; the end of the snout and the angles of the jaws bear several lappets, the fingers terminate in a star-shaped appendage, the toes are very broadly webbed and the eyes are minute and without lids.

The eggs are carried on the back by the mother, and the skin thickens and grows round the eggs until each is enclosed in a dermal cell, which is finally covered by a horny lid, believed to be formed by a secretion of the skin or else to represent the remains of the gelatinous capsule which at first surrounded the eggs. These, which may number about one hundred and measure five to seven millimetres in diameter, develop entirely within these pouches, and the young hop out in the perfect condition, without a vestige of a tail. Pairing takes place in the water, the male clasping the female round the waist. The way in which the eggs reach the back of the female has been observed in specimens kept in the London Zoological Gardens. During oviposition the cloaca projects from the vent as a bladder-like pouch, which is inverted forwards, between the back of the female and the breast of the male, and by means of this ovipositor the eggs are evenly distributed over the whole back. How the eggs are fertilized has not been ascertained.

Authorities.—G. Grünberg and A. von Klinckowström, “Zur Anatomie der Pipa Americana,” Zool. Jahrb. Anat. vii, 609; A. D. Bartlett, “Note on the Breeding of the Surinam Water Toad,” Proc. Zool. Soc. (1896), p. 595.