OLDKi; POTOMAC Ol' \Ii;(;iMA AM) .MAKVI.AM). 483 



Fossil, n.AMs mini ok kimi imiint. 



Cockpit Point was not known lo yield fossil plants until ai't(>r the pub- 

 lication of Monograph X\'. This locality is on the Potomac Piiver. The 

 Coast Line Railroad passes through a cut of consideral)le depth, situated 

 immediately on the river. This cut has exposed an ii-regular chi}- lens 

 inclosed in the Potomac sands and lying al)out 30 feet ■d\K)vo the water. 

 This lens is quite limited in extent, and where it is thickest is only about, 

 2 feet t hick. The matei-ial is a sandy clay, now hardened to a rough shale, 

 with poor cleavage. It is not well adapted for the preservation of por- 

 tions of plants of large size. As it is embedded in coarse sand and gravel, 

 the water making the deposit was exposed to strong movements which 

 tended to break up the fossils. This shale is full of plant remains and, if 

 care is exercised, many identifiable forms may be obtained, although in 

 small fragments. 



In April, 1891, Mr. David White collected here two specimens showing 

 traces of Ghjptostrobus (Taxodium) hrookensis. Some of the material from 

 the cut was thrown on the bank of the river, and in this most of the fossils 

 were obtained. The principal collections from this point was made by 

 Professor Ward and myself in a single visit on Jul}- 27, 1S93, lasting 

 only an hour or so, with no expectation of finding fossils, hence it can 

 not be taken as exhaustive. Indeed, under the circumstances, it is sur- 

 pi-ising that so many species, in such distinct forms, were found. Most 

 of the fossils were collected from the dumped material, but some from 

 the strata in place. As stated, the material is very unfavorable for the 

 preservation of good specimens; still, a considerable number of plants, 

 as may l)e judged from the following list, was obtained in the short 

 time devoted to collecting them. Four specimens occui- in the collections 

 made by Mr. Bibbins for the Maryland State Geological Survey in May, 

 1897. The following is the list of species collected here. With the 

 exception of Feistmantelia, none of them are new, having been described 

 in Monograph XV. 



Diounites Buchianus (Ett.) Born 4 specimens 



Dryopteris heterophylla (Font . ) K n 3 specimen.s 



Equisetuni vij-ginicum Font. ? _ _ o specimens 



Feistmantelia virginica Font. n. sj) . . . 4 specimens 



Glyptostrobus (Taxodium) hrookensis (Font.) Ward. 2 specimens. 



Nageiopsis heterophylla Font 1 specimen 



