BihJiograph'cal Notices, 129 



attaches to the author's remarks on the general relations of the 

 laiina under consideration. 



';Formiag the connecting link between the two Xeoga^in 

 Vl^vi «b7^^%-Dr. Gunther, "Central America possesses a 



eWnt.' ww'^^T'^ ^'^^ '^' ™«^^ constituent, 



elements so mixed that, if only certain families or genera were 

 taken into consideration, almost every district of this area could be 

 TrlT\"v ^''^ 'f''' '^' ^'''^- '' ««^^th-American region. The 

 thTnf f w'''' T'"''- ^^■"^^"""^' '^'''''S'' i^to, or is replaced by, 

 latiude.: but this change is not uniform throughout the breadth 

 of the land; the two faunas overlap each other in deep and 



TnTht 1 "f '?■'.!• ?7"^^ '°™^ ''' f-°d to preponderate 

 in the low lands of the Atlantic side, which expand into the broad 



some rxti;.^"t'" ':.'"^ "^ '''; ^^""'^^ '^^"P^^ «f °^-^-'^te elevation 

 some extend to, and even reach northwards of, the Rio Grande On 

 the Western side they are found in similar localities, but in a 

 i^arrower belt, along the Pacific coast. On the o her hamf 

 mu^erous types of the southern North-American Fauna are spread 



luL^Z^r f '"''';• '"^'"'^^"^ ^^^"° ^^' Central-American 

 plateau to the extreme limits of our area, and even beyond. This 

 southward extension of northern types is due partly to the identical 

 physical conditions of the arid tableland of sLoriand Chihuahua 

 which IS merely a continuation of that of Arizona and Xew Mexico' 

 and partly to the great altitude and temperate climate of th^ 

 Central-American plateau. 



"Thus, a boundary-line between the Xorth- and South-American 

 egions canno be drawn : the whole of Central America is a 

 transition-tracc which, unlike any other part of the world, shows 

 the most extraordinary diversity of climatic, phvsical, and meteoric 

 conditions within compararively small areas, favouring the evolution 

 of a great variety of types of genera and species, and influencing- 

 the dispersal of species from the North and South '' " 



Some expression of opinion from the author as to the ori-in of 



ih^ ^cr.^■^ f r. o "i';"7" "■'''"■ ''^^ aurnor as to the origin of 



he reptile fauna of South America .vould have been welcome ; but 

 this may have been beyond the scope of the ' Biolo-ia ' oi 

 perhaps be touched upon at the completion of the entire work 



. ' L'~ "- ^^^yi^,.LKjn ^J^ luu enure worK. 



As regr rls the systematic portion of the work, a very few words 

 must suffice-partly because the present reviewer does not feel 

 himself competent to discuss details, and partly because such a 



this journar' "'^ '^ '"^''"'^ *' *^' ""'J"^'^*^' °^ '^"^ ^'^^^^^^ «^ 



Speaking generally, it; may be affirmed that Dr. Giinther is 



disposed to regard genera and species in a broad and comprehensive 



ense. For example, he takes the genus AUiaator to include the 



caimans and jacares of Central and South America, which are 



classed bj- many other writers as a group apart, under the 



barbarous title "Caiman." Doubtless there is mich to be said in 



favour of the authors view- the non-division of the nostrils bv the 



nasals and the presence of bony scutes on the under surface iii 



Ann. ct' Mag. N. Hist. Scr. 7. Vol xi. 9 



