PROTEUS, ZOOLOGY (Proteus anguinus), in zoology, a blind perennibranchiate tailed Batrachian, inhabiting the subterranean waters of the limestone caves to the east of the Adriatic from Carniola to Herzegovina. It was long supposed to be the sole representative of the Batrachians in the cave fauna, but other examples have been added in recent years. It is a small eel-like animal, with minute limbs, the anterior of which are tridactyle, the posterior didactyle, with a strongly compressed tail, a narrow head, with flat truncate snout, minute rudimentary eyes hidden under the skin, which is usually colourless, or rather flesh-coloured, with the short, plume-like external gills blood- red; the jaws and palate are toothed. This extraordinary Batrachian has been found in a great number of different caves, but rather sporadically, and it is believed that its real home is in deeper subterranean waters, whence it is expelled at times of floods. It is often kept in aquariums, where it may turn almost black, and has bred in captivity. Proteus forms with Ned urns (Menobranchus) the family Proteidae. The second genus, which is widely distributed in eastern North America, is more generalized in its structure, having better developed limbs, with four digits, and is adapted to live in the light. But the two are closely allied, and Necturus gives us a very exact idea of what sort of a type Proteus must be derived from.
In 1896 a Proteus-like Batrachian was discovered in Texas during the operation of boiing an artesian well 188 ft. deep, when it was shot out with a number of remarkable and unknown Crustaceans. Typhlomolge rathbuni (see fig.), as this creature was called, agrees with Proteus in the shape of the head, in the absence of functional eyes, in the presence of external gills, and in the unpigmented skin. It differs in the very short body and the long slender limbs with four to five digits. It was first placed in the same family as Proteus, but the anatomical investigations of Ellen J. Emerson have led this author to believe that the real affinities are with the larval form of the lungless salamander Spelerpes, not with Necturus and Proteus. Whilst Proteus has lungs in addition to the gills, Typhlomolge lacks the lungs, and with them the trachea and larnyx. It is therefore probable that Typhlomolge is a permanent larva derived from Spelerpes, whilst we are quite unable to assign any direct ancestor to Necturus.
Another blind Urodele has recently been described as Typhlotriton spelaeus, from caves in the Mississippi Valley. It has neither gills nor lungs in the adult, and is found under rocks in or out of the water. It is not allied to Proteus. The eyes are apparently normal in the larva, but in the adult they have undergone marked degeneration.
See P. Configliachi and M. Rusconi, Del Proteo anguino (Pavia, 1819), 4; J. de Bedriaga, Lurchfauna Europas (1897), ii. 28; E. Zeller, Uber die Fortpflanzung des Proteus anguinus., Jahresb. ver. Nat. Wurttemb. (1889), p. 131 ; L. Steineger, " New Genus and Species of Blind Cave Salamanders from North America," P. U.S. Nat. Mus. (1892), xv. U5;idem," New Genus and Species of Blind, Tailed Batrachians from the Subterranean Waters of Texas," op. cit. (1896), xviii. 619; Ellen J. Emerson, "General Anatomy of Typhlomolge rathbuni," P. Boston Soc. N.H. (1905), xxxii. 43.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)