FOSSILS OF THE RANCOCAS FORMATION. 



339 



To the south of New Jersey, in Delaware and Maryland, this subdi- 

 vision of the Rancocas into two members becomes gradually obscured, 

 although the lime-sands still continue to characterize to some extent the 

 upper portions of the formation on the eastern side of the Chesapeake, 

 but at the same time the Terebratula harlani is no longer limited to its 

 former horizon at the top of the Sewell marls, but occurs frequently 

 within and even at the top of the lime-sands. The lower member also 

 changes its character, becoming less glauconitic and grayish or reddish 

 gray in color. 



Fossils. — The fossils of the Rancocas formation are less varied in spe- 

 cies, but very numerous in individuals, and at times largely make up the 

 strata, as above described. A few of the species are identical with those 

 found at lower horizons, while a few continue on into the succeeding 

 Manasquan formation, but the majority have not yet been found else- 

 where. Among the characteristic and common species found in this 

 formation, and with one or two exceptions obtained and determined by 

 the authors, are the following : 



• Verneuilina triquetra, Munst. 

 v Lingullna carinata, d'Orb. 



Pentacrinus bryani, Gabb. 

 * Goniaster mammillata, Gabb. 

 . Cidaris splendens, Morton. 



( 'idaris walcotti, Clark. 

 c? Salenia tumidula, Clark. 

 o Salenia bellula, Clark. 

 t Pseudodiadema diatretum, Morton. 

 Coptosoma speciosam, Clark. 



», Terebratula harlani, Morton. 



v Terebratula harlani, var. fragilis, Morton. 



■/ Gryphxa vesicularis, Lamarck. 



v Gryphxa bryani, var. precedens, Whit. 



i Gryphxostrea vomer, Morton. 



S Perissolax trivolva, Gabb. 

 Cavoscula annulata, Morton. 



^ Nautilus bryani, Gabb. 

 - Nautilus dekayi, Morton. 



sFlabellina sagittaria (Lea). 

 r Polymorphina communis, d'Orb. 



y/Trematopygus crucifer, Morton. 



Catopygus oviformis, Conrad. 



Ananchytes oralis, Clark, 

 v Cardiaster ductus, Morton. 

 '.Hemiaster parastatus, Morton. 

 , Hemiaster stella, Morton. 

 ,. Hemiaster ungula, Morton. 



* Cistella beecheri, Clark. 



v Idonearca medians, Whit. 

 zTeredo tibialis, Morton. 

 ^Gastrochsena americana, Gabb. 



v Pleurotrema solariformis, Whit. 



v Ammonites (Sphenodiscus) lenlicularis, 

 Owen. 



MA NASQ UA N FOE MA TION. 



Name. — The Manasquan formation * receives its name from the Manas- 

 quan river, in Monmouth county, New Jersey, where the most complete 



* Journal of Geology, vol. ii, 1894, pp. 166, 167. 

 1,1— Bull. Geol. Soc. Am., Vol. 8, 1896 



