1880.] 



NATURAL SCIENCES OF PHILADELPHIA. 



of the National Institution, 1841). The intermediate deposits 

 were classed as the Upper Marine, but subsequently under Lyell's 

 designation of Miocene. Conrad's original observations were in 

 general confirmed by his later researches, and the relations of at 

 least a great portion of the Miocene of Maryland, as well as of 

 almost tlie entire Atlantic slope, were clearly pointed out V)y 

 Lj-ell in 1845 (Proc. of the Geolog. Soc, vol. iv, p. 547). 



It is mainly in relation to this last formation that we wish to 

 draw special attention, there being but little question concerning 

 the original determination of the Eocene and Post-Pliocene 

 (Pliocene ?) deposits. That the great bulk of the deposits known 

 as the Medial Tertiary of Marjland are not sj-nchronous with 

 the South Carolina deposits classed by Tuomey and Holmes as 

 Pliocene, an assumed fact insisted upon by Conrad, and for which 

 there appears to be no evidence, an examination of the following 

 table of mollusca will clearly demonstrate : 



Lameilibranchiata of the Medial Tertiary Formations of Maryland. 



Leda concentvica. 



Anomia epTiippium,* Cardita protracta, 

 Amphidesraa caxinata,* " granulata,* 

 " subovata, Cardium laqueatum, 



Area callipleura, 



(= A. dipleura?), 

 " idonea, 

 " incile,* 

 ' ' subrostrata, 

 " Marylandica, 

 " triquetra, 

 " centenaria,* 

 " improcera,* 

 " stilicidiura, 

 Artemis acetabulum, * 

 " concentrica, 

 (=: A. elegansf], 

 Astarte vicina, 



" cuneiformis, 

 " obruta, 

 " perplana, 

 " exaltata, 

 " varians, 

 " distans, 

 " planulata, 

 " undulata,* 

 Cardita arata,* 



" acutilaquea- 



tum, 

 " craticuloides, 

 " leptopleura, 

 Corbula cuueata,* 

 " idonea, 

 " elevata, 

 " inequalis,* 

 Crassatella Marylandica, 

 " turgidula, 



" melina, 



" undulata,* 



Cytherea Sayana,* 

 " albaria,* 



Lima pajiyria, 



Lepton {?) mactroides, 



Lucina anodonia,'^ 



(=L. Americana), 

 ' ' Foremani, 

 " subobliqua, 

 " subplana, 

 '* cribraria,* 

 " crenulata,* 

 " contraeta,* 

 " divaricata,* 



Mactra incrassata, 

 " ponderosa. 

 ' ' fragosa, 

 " subcuneata, 



" delumbis, 

 (= C. idonea), Modiola Ducatellii, 

 Marylandica, Mya producta, 



Mytilus incurva, 

 Ostrea Virginica,* 

 " percrassa,* 

 Panopaa Americana, 

 " rettexa,* 

 " porrecta, 

 (=P. Goldfussi?) 



" subnasuta, 

 Isocardia fraterna, 

 " Markoei, 

 Leda liciata, 

 " acuta,* 

 " (Yoldia) laevis, 

 " (Nucula) proxima, 



