234 On the Geographical Distribution of Insects. 



ever, we meet with a few remarkable genera, and which are 

 proper to it, such as Scaphinotus and Sphaeroderus, which 

 represent our Cychrus. The Aleutian Isles, with a few of 

 whose entomological productions Eschscholtz has made us 

 acquainted, have scarcely furnished more than a few Carabidae 

 without a single new form. The large island of Terrarnova 

 should be included in this region. 



25th, The United States, to the Mississippi and the Missouri 

 on the west, and the Gulf of Mexico on the south ; a region 

 not so rich as its geographical situation might lead us to sup- 

 pose. The Coleoptera are dominant here, and present a mix- 

 ture of European and intertropical forms. Here also we find 

 Phanaeus by the side of Geotrupes, Rutela by the side of 

 Melolontha, and Gymnetis along with Cetonia, &c. The 

 most conspicuous of the genera of this order proper to the 

 region in question are Pasimachus and Dicaelus. The Lepi- 

 dopter a, particularly the diurnal section, are singularly limited 

 in numbers ; scarcely eighty species are known, and many of 

 these reappear in Brazil, and a few in Europe ; but this region 

 possesses a peculiar and very remarkable group of Papilio (P. 

 Troilus, Asterias, Glaucus, Calchas, Philenor, Villersii), the 

 analogues of which exist nowhere but in Mexico and the 

 Antilles. Among the nocturnal kinds we remark beautiful 

 species of Saturnia and Agarista, a genus of which the proper 

 native country is New Holland. The other orders, as far as 

 can be judged from the works of Say, are likewise but mo- 

 derately supplied. 



26th, Region of the Bockg Mountains, bounded on the east 

 by the Missouri and Mississippi, on the west by the ocean, north 

 by New Hanover, south by Old California ; a I'egion very 

 imperfectly known ; in its northern quarters bearing consider- 

 able resemblance to Europe, and appearing to be very rich 

 in Melasomas in its southern parts. The most remarkable of 

 the genera peculiar to it is that of Omus, belonging to the 

 tribe of Cicindelidoe, discovered by Eschscholtz in New 

 California. 



27th, Old CMifornia, Mexico, and Central America, as far as 

 the isthmus of Panama. This region admits of being sub- 

 divided at least into two others. California, although arid. 



