ECOLOGY OF ISLE ROYALE. • 261 



Gerris sp? ]S"ymphs were taken in a rock pool at Tobin Harbor 

 (IV, 2) on July 19 (30 A), and on a small stream at the head of a 

 l>og (V, 5) near Siskowit Lake (95 A). 



Aradidae. 



Aradus ahhas Berg. One specimen was taken on August 7 about 

 <^aujp on Siskowit Bay (V, 3). 



Lygaeidae. 



Lyyus pratensis L. Taken about camp at the Light-house (I, 7) 

 July 11. "One of the dark colored varieties. The species has a wide 

 distribution in both Europe and North America." H. Osborn. 



Fam'era sp. Also taken about camp at the Light-house (I, 7) on July 

 2.']. "Apparently an undescribed species.'' H. Osborn. (136 A). 



Gicadidae. 



Tihiceiii rimosa Say. var. This cicada was abundant upon the hot 

 jack pin'e ridge (I, 5) and among the birches at its base. Adult 

 specimens and a nymph skin were taken on July 8 (G. 28), 10 (G. 44) 

 and. 17 (G. 108) ; at Neutson's resort (W, 5) on'july 21 (44. A) ; in the 

 rock clearings (I, 2) on July 13 (G. G8) ; on the rock ridges on the 

 McC'argoe trail (II, 3) on July 25 (G. 147)'; in the clearing about the 

 Light-house (I, 7) on July 8; and near the head of Rock Harbor (III, 6) 

 on July 17 (G. 111). The sjjecies thus showed a decided preference for 

 the open dry situations. Prof. H. Osborn writes concerning the speci- 

 mens sent to him for determination : "These specimens agree closely with 

 a variety of rimosa occurring at Ft. Bridger, Wyoming." 



Concerning the habits of this species Osborn ('96, p. 196) states that 

 in northwestern Iowa it occui'S "on prairie land remote from timber, 

 thus indicating a habit quite different from the other members of the 

 genus." The occurrence of this species in the more or less open place 

 upon Isle Royale is thus in harmbny with its prairie habits and shows 

 that these rock openings may contain not only fonns of northern faunal 

 affinities but also those from the western plains. The occurrence of 

 these western species in open places in the northern forest region is 

 analogous to the southern prairie species found in dry or sandy places 

 in the south-eastern forests. 



Jassideac. 



Bafhoscopus pruni Prov. This leaf hopper was taken from a rock pool 

 upon a small island in Tobin Harbor (IV, 2) on July 19. 



Cocci d a c. 



Orthesia sp. This bark louse was taken July 19, at Scovill Point 

 (IV, 1). "Undescribed so far as I can discover." H. Osborn. 



