571) 



Two features of interest strike one in the distribution of the insects of 

 the Pacific slope, viz, the absence of forms characteristic of Japan and 

 China, and the presence of some European types which do not occur in the 

 Eastern (Atlantic) province. We know so little of the Phalsenid fauna of 

 China and Japan that our illustrations must be borrowed from other fam- 

 ilies and insects of other orders. Among the Phakenids there are Hydrio- 

 mena sord'idata, Petrophora Jlavata, two species of Lithostege, Selidosema, 

 Gnoplios, etc., which do not occur in the Atlantic province, and are allied to 

 species or belong to genera which occur in Europe, but do not inhabit North 

 America east of the Rocky Mountains. In other families of Lepidoptera, 

 Papilio zolicaon represents the European P. machaon, while the genus 

 Pdrnassius does not occur in the Atlantic province. The European Bom- 

 bycid genera Epicattia and Callarctia do not occur in the Atlantic province. 

 The Neuropterons genus Rhapltidia does not occur in the Atlantic States, 

 while Boreus californicus is more like the European B. hyemalis than the 

 two Atlantic species. 



On the other hand, we find in the Pacific States no such development 

 of the genus Lithosia as in Europe, no species of Zygama, no true Psych/da; 

 no such development of the genus Hepialus, and any species of Lasiocanqxi 

 are wanting in California. We miss again in the Pacific States any species 

 of Trop&a, a genus linking the Atlantic or Northeastern American entomo- 

 logical fauna with that of Northeastern Asia. California has evidently not 

 borrowed her insect fauna from Northern China or Japan. 



The main features in the geographical distribution of land-animals are 

 apparently the same with those of plants. Prof. Asa Cray has shown* that 

 "almost every characteristic form in the vegetation of the Atlantic States is 

 wanting in California, and the characteristic plants and trees of California 

 are wanting here" (/. e., in the Atlantic States). We may, on the whole, 

 perhaps say of the Californian Lepidoptera at least as Dr. Cray remarks of 

 the plants, that they are "as different from [those] of the Eastern Asiatic 

 region (Japan, China, and Mandchuria) as they are from those of Atlantic 

 North America. Their near relatives, when they have any in other lands, 



are mostly southward, on the Mexican plateau The same may 



be said of the [insects] of the intervening great plains, except that north- 



* Address at Dubuque meetiug of the Amerieau Assoc. Adv. Scieuce, Aug., 1873. 



