EISEN 



latter only those species collected in Alaska are described 

 in this paper. With the permission of Mr. E. H. Harriman 

 I have included descriptions of all the above collections in the 

 present paper, which thus becomes much more valuable and 

 exhaustive. 



The number of species found within a really limited territory 

 will probably prove a surprise to students of this group of 

 animals ; and it must be remembered that none of those who 

 contributed the collections made a specialty of this group. A 

 few specimens were collected here and others there, every col- 

 lector having some other special branch to look after. Still 

 the result is most gratifying, as the forty six new species 

 increase the total from 128 to 174. While the specimens 

 from Alaska have all been carefully gone over and all the 

 species described, the same cannot be said of other specimens 

 in my collection. Owing to unforeseen circumstances this 

 paper had to be brought to a speedy close and many species 

 had to be left out which undoubtedly would have proved to be 

 new. I have yet in my possession some fifty or more new 

 species collected on the Pacific Coasts by myself, and by Dr. 

 Stuxberg during the Vega Expedition, but time does not allow 

 me to describe them now. My object in mentioning this fact is 

 merely to show the great number of species on the Pacific coast 

 and in the arctic and subarctic zones generally. Nearly every 

 new locality is found to possess new and distinct species, which 

 seem to be much more restricted in their habitat than is the case 

 in Europe. The isolation of species in California is undoubt- 

 edly due to the lesser rainfall on this part of the coast, which has 

 prevented the species from rapidly spreading. In the north, 

 along the Alaska coast, Enchytrasidie seem to occur in count- 

 less numbers, favorable localities being found everywhere. But 

 the further south we go the scarcer become the species and the 

 higher must we go in the mountains in order to find any at all. 

 Compared with the north, Enchytrasidse in California are ex- 

 ceedingly scarce, and even during the rainy season we may 

 hunt for several days in apparently favorable localities without 

 finding any. Even in the Sierra Nevada species of this family 

 are comparatively rare. As we go further south, into Mexico, 



