190 AMPHIBIA. 



are covered by the transparent integument. The palatal teeth 

 (Siren} are arranged in rows like the teeth of some Fishes, or form a 

 curved arch at the anterior end of the palatine bones. The extre- 

 mities also are weak and reduced ; the anterior end with three or 

 four digits, and the posterior with two to five jointed digits. The 

 digits may, however, be rudimentary and be without distinct joints. 



Amongst the Tertiary remains of this group the gigantic Andrias 

 Scheuchzeri, which became famous as Homo diluvii testis, is worthy 

 of remark. 



Tribe 1. Perennibranchiata. With persistent gills, usually with- 

 out maxillary bones. The vomer and palatine bone with rows of 

 teeth. 



Fam. Sirenidae (Armmolche). With elongated eel- like body and rudimentary 

 anterior limbs, without posterior limbs. Siren laccrtina L., South Carolina. 



Fam. Proteidae (Olme). Body elongated and cylindrical ; anterior limbs 

 short, with three digits ; hind limbs placed far back, with two digits. Only 



FIG. Q29.Menobrancfius lateralis (reg-ne animal). 



two gill slits on each side. Proteus anguineus Laur. Flesh-coloured and living 

 in the subterranean waters of Carniola and Dalmatia. 



Fam. Menobranchidae. Body elongated, with tolerably broad head and four- 

 toed limbs. There are four gill slits on each side. Menobranclius later alls Say, 

 Mississippi (fig. 629). Probably holds the same relation to the genus Batra. 

 clioscps Bonap. that Siredon does to Aniblystoma (Cope). Siredon pisciformi* 

 Shaw, and maculatus Baird., Axolotl. The eggs are laid in the water either 

 singly or in masses. The larvas, when hatched, are from fourteen to sixteen mm. 

 long, have three pairs of gills, and are still without limbs. Under suitable 

 conditions they lose in the course of further development (according to Dume'ril, 

 whose observations have been several times confirmed) the gill tufts, the dorsal 

 and caudal crests, and assume the form of Aniblystoma (second sexual form). 



Tribe 2. Derotrema. Without gill tufts, usually with a branchial 

 aperture on each side of the neck, with maxillary bones, and teeth 

 which are usually arranged in one row. 



Fam. Ampbiumidae (Aalmolche). Body elongated eel-shaped, with (short 

 extremities far apart from one another. Ampliiuma L., A. trldactylum Cuv. 

 ( A. means L., with but two digits), Florida. 



Fam. Menopomidae. Of Salamander-like appearance, with four anterior and 



