694 SYSTEMATIC PALEONTOLOGY 



Occurrence. MATAWAN FORMATION. Three-quarters of a mile south- 

 east of Ulmstead Point, Anne Arundel County. 



Collections. Maryland Geological Survey, Philadelphia Academy of 

 Xatural Sciences, New Jersey Geological Survey. 



Outside Distribution. Mataivan Formation. Wenonah sand, New 

 Jersey. Ripley Formation. Exogyra costata zone. Extreme top of zone, 

 Pataula Creek, Georgia. 



TELLINA (ARCOPAGIA) GABBI n. sp. 

 Plate XLII, Fig. 2 



Peronccoderma georgiana Gabb, 1876, Proc. Acad. Nat. Sci., Phila., p. 308. 

 Peronccoderma georgiana Johnson, 1905, Ibidem, p.* 16. 

 Peronccoderma georgiana Weller, 1907, Geol. Survey of New Jersey, Pal., 

 vol. iv, p. 617, pi. Ixx, figs. 4-6. 



Description. " Shell small, thin, flattened ; elongate, beaks subcentral 

 in one case in the middle, in another a little posterior ; cardinal margins 

 sloping about equally towards both ends. Anterior end prominently and 

 narrowly rounded ; posterior rounded, subtruncate ; base broadly and regu- 

 larly convex. Surface marked by fine, regular concentric lines. Hinge 

 composed of minute teeth. Length 1.2 in, width 0.8 in." Gabb, 1876. 



Type Locality. Pataula Creek, Georgia. 



Shell rather large for the genus, compressed, ovate, trigonal in outline ; 

 umbones flattened, inconspicuous, not over-topping the dorsal margins, 

 slightly posterior; umbonal angle approximately 135; dorsal margins 

 oblique, the anterior very gentle, the posterior moderately steep ; anterior 

 lateral margin broadly and smoothly rounded, the posterior obscurely 

 truncate ; base line broadly arcuate : external surface sculptured with very 

 thin, concentric lamina?, their dorsal edges free, but closely appressed; 

 ligament external, opisthodetic, mounted on a nymph almost half the 

 length of the dorsal margin ; hinge concentrated, that of the right valve 

 armed with two short, divergent cardinals and an anterior lateral ; hinge 

 of left valve and characters of adductor scars and pallial sinus unknown. 



Weller suggested that this species might properly be referred to Tellina, 

 but he hesitated to do it because Gabb's name was already preoccupied by 



