Nov. 13.1873] 



NATURE 



29 



clusively constructed to pass the whole of their lives in 

 trees that they can move along the ground only with diffi- 

 culty — such is the case with the sloths. Porcupines, which 

 in the old world have short tails, in the new world have 

 long and prehensile ones. An animal allied to the Badger 

 — the Kinkajou {Ccrcolcptes candivo/v!ilus)—s\m\\^x\y 

 acquires in South America a long and prehensile caudal 

 appendage. Even the Fowl and Peacock Order of Birds 

 becomes in South America more strictly arboreal than 

 elsewhere (being represented by the Curassows), and the 

 very geese find there a congener {Palamciiia) specially 



adapted to dwell in trees and destitute (like the frog 

 Pliyllomedusa before mentioned) of a web-like membrane 

 between the toes. 



We have now advanced a further stage in seeking a 

 reply to the question, " What is a Frog ? " We have now 

 viewed it in the light to be derived from a consideration 

 of the more noteworthy forms of the frog's order. 



We may next inquire what are its next nearest allies ? 

 What other animals of the class Batrachia constitute an 

 order which approaches nearest to the frog's order 

 Anoiira ? 



Almost every pond in England which harbours frogs, 

 harbours also those little four-legged, long-tailed, soft 

 skinned creatures termed Efts or Newts (of the genus 

 T?'itoi!) familiar to every schoolboy. 



These Newts which are thus by circumstances placed 

 actually in juxtaposition with the frog are also zoologi- 

 cally his nearest allies outside his own (frog and toad) 

 order. Like the frog they undergo a metamorphosis, at 



first appearing as Eft-tadpoles (with elongated external 

 gills, but devoid of limbs), subsequently losing the gills 

 and acquiring limbs. Efts, as is manifest, are widely 

 and strangely different in form from frogs and toads. 



Thus is justified the assertion before made as to the 

 far less exceptional form of the human body than that 

 of the frog. For when, amongst Mammaha, we go 

 outside that ordc-r to which IVIan belongs, we find in 



his class other creatures (insect-eating, flesh-eating, and 

 of the squirrel kind) which more or less closely re- 

 semble some of the lower members of man's order. 

 When, however, amongst Batrachia, we go outside that 

 orde?- to which the frog belongs, we find in his class no 

 creatures whatever which present anything like such an 

 approximation to any members of the frog's order as is 

 presented by the mammals above referred to certain 

 members of man's order. 



The Efts (or Newts) with their alHes — hereinafter noticed 

 — constitute the second order Urodela of the class Ba- 

 trachia. 



This order is very unlike the first and already described 

 order {Anourd), in that it is composed of creatures which 

 in many respects are strangely divergent ; and though 

 most of the species more or less resemble our own Efts (or 

 Newts) in shape, yet the Urodela d.x<i\exyiz.x from consti- 

 tuting such a homogeneous group as are the Anoicra. 



It will be well now to review some of the more striking 

 forms contained in the order. 



The Land Eft {Salainandra), though common in Holland 

 and France (as well as the rest of Europe), is unknown in 

 this country. 



Genera allied to the European genera Triton and Sala- 

 maiidra, and to the American genus Ainbly stoma, may 

 have the body and tail more and more elongated and the 

 legs reduced, as in Spelerpes, Chioglopa, and CEdipina, 

 till they attain the condition of Batrachoceps. The 

 greatest excess of this development, however, is found in 

 the North American genus AmphiiiDia, the minute limbs 

 of which have either three or two toes, according to the 

 species. These creatures are called by the negroes 

 " Congo Snake," and are quite erroneously regarded as 

 venomous. 



The largest existing Urodele — the gigantic Sala- 

 mander {Cryptobranchi(s) — is found in Japan, where it 

 attains a length of 5 or 6 feet. A closely allied species 

 inhabits China, and during the tertiary period one also 

 inhabited Europe, the fossil skeleton of which being 

 strangely supposed to be that of an antediluvian man 

 received the curious appellation, " Homo diluvii testis." 



In Cryptobranchus (as in all the Urodela yet enume- 

 rated except Amphiiima), though the young have gill 



openings and external gills, the adults are devoid of both. 



In a North American genus, however {Menopoma), 

 which, though smaller in size, closely resembles Crypto 

 branchus in figure, there is a permanent gill opening, 

 though the gills themselves disappear in the adult, and 

 the same is the case with Ainphiuuia. Thus in these 

 animals the metamorphosis is less complete. 



In the subterranean caverns of Southern Austria 

 (Carniola and Istria) is found the Proteus. This is an 

 elongated Urodele, with'slender limbs, and but two toes 



