1971] 
Barr — Trechoblemus 
141 
Figure 1. Trechoblemus westcotti , new species. Hillsboro, Washington 
County, Oregon. Holotype male, length 4.6 mm. 
small, burrowing cychrines of the genus Maronetus are endemic 
to the southern Applachians, but are more closely similar to cychrine 
genera of the Pacific Northwest than they are to other eastern 
cychrines (Barr, in press). The subgenus Amerizus of the large 
genus Bembidion includes only two species, B. ( A .) oblongulum 
Herbst in the Northwest and B. (A.) wingatei Bland in the southern 
Appalachians (Lindroth, 1961). Both of these groups, like Tre- 
choblejnus-Pseudanophthalmus , are more or less humicolous or sub- 
terranean. Within the large, widely-distributed genus Pterostichus , 
the species of the California-Northwest subgenus Ilypherpes share 
a close similarity in appearance and habits with those of the Appa- 
lachian subgenus Haplocoelus (cf. Barr, 1969, footnote p. 80). 
Until both subgenera have been carefully studied, however, it is 
not possible to state whether these similarities are the result of 
phylogenetic relationship or convergence. 
The relatively few close ties between the Pacific Northwest and 
Appalachian forest carabid faunas do suggest, however, that the two 
faunas have been isolated from each other for a long time. The 
beginning of the period of isolation presumably began in the Miocene 
with the establishment of the Great Plains. If the Trechoblemus- like 
ancestors of Pseudanophthalmus arrived in North America via a 
Bering land bridge, their arrival was probably pre-Miocene. Cer- 
tainly the considerable diversity (approximately 20 species groups 
