38 CBETACEOTJS DEPOSITS OF THE EASTERN GULF REGION. 



to the zone of Exogyra costata in the eastern Gulf region only 5 are known below that zone in 

 the Carolinas. 



Of the 11 Peedee species common to the Exogyra costata zone of the eastern Gulf region 

 the following 10 are regarded as peculiarly characteristic of that zone: 



Species especially characteristic of Exogyra costata zone in the Carolinas. 



Mollusca — Continued. 



Liopistha protexta Conrad. 

 Turritella vertebroides Morton. 

 Nautilus dekayi Morton. 

 Sphenodiscus lenticularis (Owen). 

 Belemnitella americana (Morton). 



Mollusca: 



Ostrea subspatulata Forbes. 

 Exogyra costata Say (typical specimens) 

 E. costata var. cancellata Stephenson. 

 Lima acutilineata (Conrad). 

 Plioladomva littlei Gabb. 



It is on the evidence of the species just enumerated that the Peedee sand is correlated with 

 the zone of Exogyra costata of the eastern Gulf region. 



New Jersey. — In New Jersey the species Exogyra costata is limited in range to the Mon- 

 mouth group, which includes the Mount Laurel sand, the Navesink marl, and the Redbank sand. 

 Of the 127 species restricted to the zone of Exogyra costata in the eastern Gulf region, 3 species 

 are known in the Rancocas formation, which overlies the Monmouth group; 29 species, question- 

 ably 32, in the Monmouth; 19 species, questionably 24, in the Matawan group above the Mer- 

 chantville clay marl, its basal formation; 10 species, questionably 11, in the Merchantville 

 clay marl; and 2 species, questionably 3, in the Magothy formation. Of the 32 species common 

 to the Monmouth group, 16, questionably 18, are restricted to that group, and 4, questionably 5, 

 range down only into the Wenonah sand, which forms the uppermost formation of the Matawan 

 group. Of the 18 restricted species in New Jersey the following are regarded as especially 

 characteristic of the Exogyra costata zone: 



- pi <■.', s especially characteristic of the Exogyra costata zone in New Jersey. 



Mollusca: 



Cucullaea littlei (Gabb). 

 Exogyra costata Say. 

 Pecten venustus Morton. 

 Dianchora echinata Morton. 

 Plioatula urticosa (Morton). 

 Cuspidaria jerseyensis W'eller. 

 Cardium kummeli Weller. 

 Xenophora leprosa i Morton i. 



The species enumerated are taken to indicate the synchroneity of the Monmouth group 

 with the Exogyra costata zone of the eastern Gulf region. 



Texas. — The fauna of the Navarro formation of Texas has long been correlated with the 

 fauna of the Eipley formation of Tippah County, northern Mississippi. Although a critical 

 comparison of the two faunas has not been made it is known that many species regarded as 

 characteristic of the Ripley beds of Tippah County, and hi general of the Exogyra costata zone 

 of the eastern Gulf region, are common to the Xavarro formation. There is abundant reason, 

 therefore, for regarding the correlation as correct. Little is known of the fauna of the Taylor 

 marl, which in Texas intervenes between the Austin chalk and the Navarro formation. The 

 exact correlation of the Taylor marl is therefore one of the problems awaiting solution. 



VERTEBRATES. 



A few vertebrate remains represented by teeth and fragmentary bones have been found 

 in this zone. Teeth of the following: fishes have been identified: 



Moll usca — Continued . 



Turritella vertebroides Morton. 

 Anchura abrapta Conrad . 

 Bulla macrostoma Gabb. 

 B. mortoni Forbes. 

 Nautilus dekayi Morton. 

 Sphenodiscus lenticularis (Owen). 

 Belemnitella americana (Morton). 



Enchodus ferox Leidy (identified by J. W. Gidley 

 Enchodus? petrosus Cope (identified by J. W. Gidley i. 

 Ischyrhiza rnira Leidy (identified by J. W. Gidley . 



Fish remains from zone of Exogyra costata. 



Galeocerdo sp. (shark) (identified by J. W. Gidley). 

 Corax falcatus Agassiz (shark) . 

 Lamna texana Roemer (shark). 



