898 The American Naturalist. [November, 
remaining regions. The number of peculiar species in all 
departments of animal life is large. It presents the greatest 
development of the eastern reptile life. Sixteen genera of 
Reptiles and eight of Batrachia do not range to the northward, 
while ninety-nine species are restricted in the same manner. 
The peculiar genera which occur over most of its area are: 
SAURIA : TESTUDINATA: 
Anolis, Macrochelys. 
LORICATA : 
SERPENTES: Sitio 
Elaps, 
Haldea, BATRACHIA: 
Cemophora, Engystoma, 
Tantilla, Manculus, 
Compsosoma, Amphiuma, 
Farancia. Siren. 
I have omitted from this list ten genera which are restricted 
to one or the other of its subdivisions. The Siren, the Cemo- 
phora, the Anolis, and the Alligator, are the most striking of 
the above characteristic genera. No genus of lizards is pecu- 
liar excepting Anolis, which has its greatest development in 
other than the Nearctic continent. Among Serpents a few 
genera of Neotropical character extend eastward along the re- 
gion of the Mexican Gulf, as far as the Atlantic coast, which 
are not found in any of the northern regions; such are Comp- 
sosoma, (Central American); Tantilla, and Elaps (Sonoran). On 
the other hand, Abastor, Virginia, Haldea, and Storeria, embrace 
serpents which it shares with the Eastern region. 
This region is the headquarters of the Batrachia, especially 
of the tailed forms. The majority of species of the tailless 
genera are found here, especially of Hyla (tree-toads), Rana, 
and Chorophilus. 
There are no less than nine genera of birds which do not, or 
only accidentally, range northward of this district. They are, 
according to Allen: 
