CHAP. XlV.j 
THE NEOTROPICAL REGION. 
57 
Buprestidse. — In this family there are no peculiar genera. 
All the large South American groups are absent, the only im- 
portant and characteristic genus being Stenogaster. 
Longicorns. — This important group is largely developed, the 
country being well adapted to them ; and their distribution 
presents some features of interest. 
In the Prionidse there are 6 peculiar genera, the largest being 
Holonotus with 3 species ; two others, Derotrachus and Mallaspis, 
are characteristic ; 3 more are common to South America, and 1 
to Cuba. The Cerambycidse are much more numerous, and there 
are 24 peculiar genera, the most important being Sphenothecus, 
Entomosterna, and Cyphosterna ; while Crioprosopus and Metalep- 
tus are characteristic of the sub-region, although extending into 
South America; about 12 Neotropical genera extend to Mexico 
or Guatemala, while 12 more stop short, as far as yet known, at 
Nicaragua. Lamiidae have a very similar distribution ; 13 genera 
are peculiar, the most important being Monilema, Hamatoderus, 
and Carneades , while Fhcea and Lagochirus are characteristic. 
About sixteen typical Neotropical genera extend to Mexico, and 
15 more only reach Nicaragua, among which are such important 
genera as Anisopus, Lepturgus , and Gallia. 
The land-shells are not sufficiently known to furnish any 
corresponding results. They are however mostly of South 
American genera, and have comparatively little affinity for those 
of the Antilles. 
Relations of the Mexican sub -region to the North and South 
American Continents. — The sudden appearance of numerous 
South American forms of Edentata in temperate North America, 
in Post-Tertiary times, as narrated in Chapter VII., together 
with such facts as the occurrence of a considerable number 
of identical species of sea fish on the two sides of the Central 
American isthmus, render it almost certain that the union of 
North and South America is comparatively a recent occur- 
rance, and that during the Miocene and Pliocene periods, they 
were separated by a wide arm of the sea. The low country 
of Nicaragua was probably the part submerged, leaving the 
highlands of Mexico and Guatemala still united with the North 
