1920.1 NATURAL SCIENCES OF PHILADELPHIA. 93 



there both in species and individuals."'^ Many ericaceous species 

 which are shown by studies in other regions to prefer mediacid or 

 high subacid soils thrive in the Pine-barrens, whereas those requir- 

 ing less acid conditions, such as the Pyrolas and Chimaphilas, are 

 there infrequent, rare or unknown. On the other hand, plants 

 which in the north are regarded as " calciphiles " — circumneutral 

 soil plants — extend into southern New Jersey only along the marginal 

 regions. To give but one example, Gentiana crinita is, as noted by 

 Stone, a rarity in southern New Jersey; but in the Lindenwold bog 

 it grows in wonderful abundance, being limited to the lower levels, 

 where the calcareous strata outcrop, and neutralize the soil. 



Southern Delaware. 



During March, 1919, the writer visited the region around Mills- 

 boro, Sussex County, Delaware, to study the soil acidity as related 

 to the distribution of native plants. The selection of this particular 

 place was due to the reported occurrence there of the box-leaved 

 huckleberry, Gaylussacia brachycera (Michx.), of which living speci- 

 mens were desired. The earliness of the trip was determined by the 

 fact that this plant is an evergreen and seemed likely to be most 

 readily found before the leaves had developed on the majority of 

 other plants. After several days', search a single small colony of 

 the Gaylussacia was located, many acidity tests of the soils met 

 with being carried out in the course of the trip. The results of these 

 studies are here presented; since this region is less well known than 

 those previously described, it is treated in greater detail. 



The Millsboro region lies on that part of the Atlantic Coastal 

 Plain known as the Delaware Peninsula or "Eastern Shore" (of 

 Chesapeake Bay) District, about 16 km. (10 miles) back from the 

 sea coast, and a like distance from the southern boundary of the 

 state of Delaware. It is best reached by train on the Franklin City 

 branch of the Delaware, Maryland and Virginia Railroad, a part 

 of the Pennsylvania system, running south from Wilmington, Dela- 

 ware. It is a region of low relief, the Indian River, which traverses 

 it, being a tidal estuary, while the maximum elevation is little over 

 12 meters (40 feet) above sea level. The geological formation ex- 

 posed at the surface of the ground is the Talbot formation, of Pleis- 

 tocene age, consisting of unconsolidated sand, with occasional 

 lenses of gravel and of clay, and the soils correspond in character. 



5The Plants of Southern New Jersey. . . . Trenton, 1911, p. 617. 



