86 



POSSIL ESTHERI^. 



Fig. 5. 



Estheria o\a.Xa,from Richmond. Magnified 

 and of natural size. After Lyell. 



as tlie " Posidonomya minuta," may not be allied to Cypris rather than to any genus of 

 the Mollusca. 



The larger form figured by Lyell (fig. 6 a, here copied as fig. 5 a) is stated to resemble 



Cyclas in outline ; oval and inequilateral ; ^ths inch in 

 diameter. It was from Hardin's pit, north of Blackheath, 

 near Richmond, Eastern Virginia. 



The smaller one (fig. 6 h, here copied as fig. 5 h), ^ths 

 inch in diameter, is described as being more convex than 

 the other ; " resembles a young Astarte, but may perhaps 

 be the young of the preceding." Erom Hardin's pit, and 

 also from Creek mines, south of Blackheath, Virginia. 



The same fossils were found at the Deep-run pits, at 



the northern extremity of the coal-field. " They occur in 



such immense numbers (at Blackheath) as to divide the shale, 



like plates of mica, into very thin laminae. Every fresh surface exhibits a layer of them." 



In 1856 Dr. I. Lea read before the Academy of Natural Sciences of Philadelphia,^ 



some notes on the " New Red Sandstone Formation of Pennsylvania," and stated that in 



the greenish and blackish shales near Phoenixville, on the Schuyl- 

 kill, he found two forms of " Posidonia " {Estheria) both difiering 

 apparently from those figured by Sir C. Lyell ; and he named 

 them the P. ovata and P. parva, " the first being about ^''gths of 

 an inch in transverse diameter; the latter more rotund, and about 

 Igths of an inch in transverse diameter." 



Prof. E. Emmons in his ' Geolog. Report of North Carolina,' 

 1856,^ p. 337, describes and figures two forms of Estheria as 

 Posidonia multicostata and P. triangularis from the upper portion 

 of the Deep River series in Chatham Co., North Carolina. Ac- 

 cording to Mr. Conrad,® the former of these " had previously been 

 indicated by Mr. Lea under the name of P. ovata from specimens 

 obtained at Phoenixville ; and probably the latter was also indi- 

 cated under the name of P. parva from smaller specimens than 

 Estheria ovata (P. triangularis, thosc presented tMs evening, but likewise obtained from the same 



Emmons), from North Caro- -, -,•, „ 

 After Em. locallty." 



Fig. 6. 



Estheria ovata (P. multicostata, 

 Emmons), from North Caro- 

 lina, magnified. After Em- 

 mons, t 



Fig. 7. 



Una, magnified, 

 mons. 



The two Estheria above alluded to are figured and described 



^ 'Proceed.,' vol. viii, p. 77. 



2 la Silliman's 'Americ. Journ. Sc.,' new series, vol. xxiv, p. 427, is a notice of Emmons's 'Geo- 

 logical Report of the Midland Counties of North Carolina,' 1856, with remarks by Professor 0. Heer on 

 the Plants noticed in it. 



2 'Proceed. Acad. Nat. Sciences Philadelphia,' for 1857, p. 150. 



