106 Bulletin 1, Biological Society of WasJiington, 1918. 



lected on and near the island, that it was necessary to de- 

 scribe as new species. They are, respectively, the bat, 

 My otis tvinnemana, and the shrew, Microsorex winnemana. 16 



The river shores near Plummer's Island, while not so 

 assiduously explored as the island, have yielded many inter- 

 esting species. From the Virginia side may be mentioned 

 the southern flower fly Meromacrus cruciger, the beetles 

 Cychrus andrewsii and Pterostichus approximatus , and the 

 cicada, Melampsalta parvula. The Maryland shore has 

 yielded specimens unique in local collections of the small 

 locustid, Falcicula liebardi, and of the robber fly, Proctacan- 

 thus rufiventris. 



Upstream from Plummers Island are: the so-called Pin- 

 natifidum bluff, sole locality for the little fern, Asplenium 

 pinna tifidum, Stubblefield Falls, on the bluff near which 

 grows sweet birch, Betula lenta, the mouth of Scotts Run, 

 notable for its fine colonies of hemlocks and walking fern, 

 Cupid's Bower Island, 75 with a fine stand of large hollies 

 (Ilex opaca) and Difficult Run, an interesting locality and 

 excellent collecting spot, where a few species have exclu- 

 sively been collected, examples being Scutellaria versicolor, 

 Da sy stoma laevigata, and Cirsium virglnianum. 



A short distance above Difficult Run begins the Great 

 Falls vicinity, one of the best marked and most interesting 

 collecting areas in the whole Washington region. No reason 

 is apparent why the environs of this chief fall and greatest 

 rock-bound gorge of the Potomac should be the sole haunt 

 in our area of so many species of animals and plants, but 

 the fact remains that the area is thus very strongly char- 

 acterized. Only in this stretch of the river valley have been 

 found such shrubs as Rhus aromatica. Viburnum pubescens 

 and Primus pumila. Two rock-loving plants, Selaginella 

 rupestris and Polypodium polypodioides, have been collected 

 solely at Great Falls, and they are associated with a cliff 

 flora, which, though not peculiar, is characteristic. This 

 assemblage includes also the hairy fern, Cheilanthes lanosa; 



75 This name is derived from the language of the Indian tribes which 

 once inhabited the region ; it signifies beautiful island. 



76 The roach (Cryptocercus punctulatus) has been found only here. 



