Xatural History of District of Columbia — McAtee 81 



From the foregoing list and quotations it is evident that 

 the Powdermill Bogs contain many plants that are abund- 

 ant in the Pine Barrens. Twenty-six 5S of the species are 

 among those mentioned by Stone (op. cit., pp. 76-78) as 

 characteristic of the Pine Barren flora and their presence 

 must be regarded as incontestable evidence of relationship. 

 In addition to Pine Barren plants, the Powdermill Bogs, 

 small as they are, 54 have yielded certain species of insects 

 which previously had been known only from Pine Barrens. 55 

 These include a crane-fly (Molophilus novacaesariensis Alex- 

 ander), a deer-fly (Chrysops brlmleyi Hine) and a bee 

 (Dolichochile melittoides Viereck). One other deer-fly 

 (Chrysops vitripennis Shannon) described from these bogs, 

 and a Syrphid (Microdon scitulus Williston) known pre- 

 viously only from Florida, probably pertain to the Pine 

 Barren fauna. 



It is worthy of note, also, that a species of shrew (Sore® 

 fontinalis) was described from one of the Powdermill bogs, 

 and that all specimens thus far caught came from similar 

 situations. Synaptomys cooper 7, very local in the region, 

 and Condylura cristata also occur in these bogs. 



63 Four other true pine-barren species are common in the neighborhood. 

 Also 41 other species of the bogs are plentiful in the Pine Barrens. 



64 The largest has less than an acre of actual bog. 



65 Speaking of insects of the New Jersey Pine Barrens, Dr. John B. 

 Smith says : "The species on the whole resemble those of more Southern 

 States and Georgian or even the Floridian forms are not uncommonly met 

 with, and yet the only trace of real boreal species has been found in the 

 deep cold swamps of Ocean County." (The Insects of New Jersey, Ann. 

 Rep. N. J. State Mus., 1909, (1910) p. 30.) 



This is eminently true also of the plants of the Pine Barrens, numerous 

 Northern forms here finding their Southern limit (at least so near the 

 coast) among a flora closely related to that of the Southern Atlantic 

 States. Among such Northern species may be mentioned Potamogeton 

 Oakesianus, P. confervoides, Sporobolus uniflorous, Carex trisperma, C, 

 livida, Hypericum boreale, Corema conradii, Utricularia intermedia, Nemo- 

 panthus mucronatus, Solidago uniligulata and Aster memoralis. 



In the local Magnolia bogs this element is represented by Dryopteris 

 simulata, Unifolium canadense, Sanguisorba canadensis, Rubus hispidus, 

 Hypericum canadense, C'hamae daphne calyculata (Glenburnie) and Vibur- 

 num cassinoides. 



The prevailing affinities of the Pine Barren and Magnolia bog floras 

 being austral, such instances of the presence in them of boreal plants 

 weigh against the importance of temperature control. Obviously tempera- 

 ture control cannot restrict to the same small bog, plants, which, on the 

 basis of the climate of their respective ranges, presumably have almost 

 opposite temperature requirements. 



