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ANALYSIS OF CONTENTS OF EACH VOLUME. 
1. The ‘Introductory Volume’ includes the general preface to the whole work, 
Zoology, Botany, and Archeology, a complete list of the subjects contained in each 
Volume, general statistics, maps, &c. The ‘Contents’ of this Volume, which forms 
the first of the entire series, are given in detail on p. li. 
ZOOLOGY. 
2. Mammatia: by E. R. Alston, with an Introduction by Dr. P. L. Sclater. 
The author of this Volume died on March 7th, 1881, before the enumeration of the 
species was concluded. The MSS., however, of the Supplement (pp. 203-212) was 
left by Mr. Alston in an almost complete state, and was finished by Mr. O. ‘Thomas in 
1881. Vhe Tables (I-VIIIL.), printed in the Introduction, were drawn up at our 
request by the author shortly before his death, and Dr. P. L. Sclater gives an 
analysis of them in his Introductory remarks on the subject (pp. x—xix), published in 
1882. The total number of species enumerated is 181, of which a complete list is 
given in the Introduction (pp. iv-ix). These fall into five categories: (i.) Nearctic, 48 ; 
(ii.) Neotropical, 65; (ili.) Neogean, 17; (iv.) Autochthonous, 47; and (v.) Intro- 
duced, 4 (AZures). The eight Tables drawn up by the author show: I. General dis- 
tribution; II. Nearctic species (17) found in the Northern States of Mexico, but not 
recorded from south of 25° N. lat.; iI. Nearctic species (18) found in Central and 
South Mexico, but not recorded from south of the Isthmus of Tehuantepec; 
IV. Nearctic species (8) extending to Guatemala and Honduras, but not recorded 
from south of Nicaragua; V. Nearctic species (5) extending to Costa Rica and 
Panama, but not recorded from south of the Isthmus of Panama; VI. Species (17) 
common to the Nearctic and Neotropical Regions; WII. Species (47) peculiar to 
Central America, or not yet ascertained to occur elsewhere; VIII. Distribution of the 
Neotropical genera. Dr. Sclater (p. xiv) summarizes the analysis of the Central 
American Mammal fauna as follows :—“It may fairly be said that (excluding the 
introduced Mures) at least 100 of the constituent species are essentially Neotropicalin 
their character or have Neotropical! affinities, while of the remainder not above 60 can 
be said to be decidedly Nearctic. There is therefore no doubt that the Central 
American isthmus, at any rate as far north as Tehuantepec, should be assigned to 
the Neotropical Region, of which it should be deemed to constitute a distinct province, 
characterized (1) by the incursion of a considerable number of Nearctic forms, 
especially in the northern districts, (2) by the presence of a certain number of peculiar 
