NOVKMBEE 4, 1898.] 



SCIENCE. 



617 



lina,* altitude 6,000 feet, and Travellers' 

 Eepose, "West Virginia,* altitude about 

 3,000 feet. The shrew is recorded from 

 Eoan Mountain f and from the higher 

 mountains of central Pennsylvania. J Both 

 of these animals Qccurred also in consider- 

 able numbers among the loose rocks of the 

 talus at the narrowest part of Fort Valley, 

 altitude 750 feet.g This boreal colony was 

 completely surrounded by the upper austral 

 fauna, which extended more than a thous- 

 and feet above it. The mammal fauna of the 

 talus slope was not made up exclusively of 

 these two species. As might be expected, 

 such abundant, freelj' roaming austral forms 

 as the wood rat (^Neotoma pennsylvanlca) , 

 white- footed mouse {Peromyscus leucopus 

 leucopiis), and chipmunk {Tamias striatus 

 striatus), were often caught in traps set 

 among the loose rock masses. These com- 

 mon species would naturally wander from 

 the woods over the comparatively small 

 area of the rock slide in search of food. A 

 single short-tailed shrew {Blarina brevi- 

 Cauda) was taken there also. This animal, 

 however,ranges freely into the boreal zone.|| 

 As I have already said, the talus sloped 

 abruptly to the edge of Passage Creek. It 

 was in no way peculiar, but had all the 

 well-known characteristics of such forma- 

 tions. It supported a very scant tree 

 growth. The rock fragments were over- 

 grown with lichens, and in protected places 

 there were large mats of moss and ferns, 

 but I found no sphagnum. At the point 

 where my temperature observations were 



* Bailey, Proo. Biolog. Soo. Wasbington, XI., p. 

 130, May 13, 1897. 



t Merriam, North American Fauna, No. 10, p. 66, 

 December 31, 1895. 



J Rhoads, Proc. Acad. Nat. Sci., Philadelphia, 

 1897, p. 223, May, 1897. 



? The altitudes of localities in this region are from 

 the Luray sheet of the United States Geological Sur- 

 vey Topographic Map. 



liSee Miller, Proo. Boston Soc. Nat. Hist., XXVIII., 

 p 38, April 30, 1897. 



made, a widely open cavity had been formed 

 beneath some unusually large rock frag- 

 ments held from slipping downward by the 

 roots of trees. From this cavity at the base 

 of the talus, as well as from smaller ones on 

 its sides, there was a constant outpour of 

 cold, damp air. This was especially no- 

 ticeable on hot, still days, when the air 

 currents kept the ferns about the mouths 

 of the crevices continually waving, while all 

 other vegetation was motionless. From 

 the large cavity to the edge of the water 

 was a distance of about ten feet. The 

 rocky bed of the stream at this point was 

 onlj' some twenty feet wide. On the oppo- 

 site side of the stream was a flood -plain, 

 perhaps twenty yards across. It was very 

 irregular in surface, and consisted merely 

 of masses of sand brought down from the 

 valley above during freshets and lodged 

 among the rocks. The flood-plain was well 

 wooded, first with a fringe of shrubs and 

 further back from the stream bed with a 

 vigorous growth of trees, such as I have 

 already described. Beyond the flood-plain 

 rose the gradual slope of Three Top Moun- 

 tain. Although parts of the flood-plain 

 afforded what appeared to be perfect shelter 

 for red-backed mice and smoky shrews, the 

 most careful trapping failed to bring to 

 light anything but the common upper aus- 

 tral mammals. Colonies of pine mice (Mi- 

 crotus pinetorum) occupied places that were 

 sufSciently sandy, and white-footed mice 

 abounded. I also detected the work of a 

 mole which appeared to be that of Scalops 

 aquaticus. It is safe to say that at this 

 point the tj^pical boreal species were strictly 

 confined to the talus, the more sedentary 

 austral forms to the flood-plain and warm 

 mountain sides, but that the more active 

 and abundant austral species wandered 

 freely in search of food. 



For temperature observations I estab- 

 lished four stations. Station 1 was on the 

 flood-plain at the base of Three Top Moun- 



