16 
Assembly 
now, we believe, conceded to be of greater extent than in Europe ; and 
this is attributed mainly to two causes : One is to be found in the large 
masses of water in the interior, equalizing the temperature to a great 
extent throughout the Union ; the other is the existence of mountain 
ranges extending in a northeastern and southwesterly direction, com- 
pensating by their elevation for the 'difference of latitude. 
The State of New-York, independent of its extent of surface, (com- 
prising an area of 64,000 square miles,) in its latitudinal position is such 
that it constitutes the northern limits of many southern species, and the 
southern boundary of many animals usually considered as arctic or 
^ northern species. Hence we find the Didelphis virginiana or opossum, 
the Cailiaj'tes aura or turkey buzzard, the Scaphiopus solitarius, the 
Hemulon chrysopteron^ and others, appearing in our State from the 
south ; whilst the Stemmatopus cristatus, Surnia nyctea, Somateria 
mollissima, and, if I am correctly informed, even the Cervus tarandus, 
appear not far from our limits on the north. The distribution of species 
has been also affected by the hand of man. We refer not particularly 
to those species which have been domesticated, and rendered subser- 
vient to the wants of man ; but to those artificial water communications, 
by means of which the Cyclea cenea, the geographic tortoise, and other 
inhabitants of the great lakes, have transferred their abodes to the waters 
of the Hudson. 
There are, however, limits to the geographical distribution of ani- 
mals ; and the study and determination of these limits forms, at the 
present day, one of the most interesting objects of inquiry to the zoo- 
logist. But in order to establish this point with the requisite degree of 
exactness, it is scarcely necessary to observe that the species themselves 
must be first previously well determined ; and accordingly, at the outset 
of our inquiries, we are met with difficulties arising from a want of a 
due discrimination of species. In the course of our final report, it will 
be perceived that many species, hitherto considered as identical with 
those of Europe, are treated as specifically distinct. 
In cases where species have been observed north and south of the 
State, I have not hesitated to include them among the animals of New- 
York, although I have not had the good fortune to meet with them. 
Such, however, will undoubtedly be found ; and their number, it will 
be perceived, is comparatively small. 
