330 SYSTEMATIC PALEONTOLOGY 



Genus BORNIA Philippi. 

 BoENiA MACTROIDES (Conrad). 

 Plate LXXXVITI, Figs. 6, 7, 8. 



Lepton mactroides Conrad, 1834, Jour. Acad. Nat. Sci. Phila. vol. vii, 1st ser., p. 151. 

 Lepton mactroides Conrad, 1838, Fossils of the Medial Tertiary, p. 19, pi. x, fig. 5. 

 Lepton maciroides Conrad, 1863, Proc. Acad. Nat. Sci. Phila., vol. xiv, p. 577. 

 Lepton mactroides Meek, 1864, Miocene Check List, Smith. Misc. Coll. (183), p. 8. 

 Bornia mactroides Dall, 1900, Trans. Wagner Free Inst. Sci., vol. iii, pt. v, p. 1150. 



Description. — " Shell triangiilaT, subequilateral, thin, convex, smooth 

 and polished; beaks prominent; central; basal margin straight; posterior 

 extremity less obtusely rounded than the anterior. Length less than 

 half an inch." Conrad, 1834. 



Length, 10 mm.; height, 7.2 mm.; diameter. 2 mm. 



Occurrence. — Choptank Formation. Governor Run, 2 miles south 

 of Governor Run, Jones Wharf, Peach Blossom Creek, Dover Bridge. 



Collections. — Maryland Geological Survey, Johns Hopkins University. 



BORNIA TRIANGULA Dall. 



Plate LXXXVIII, Figs. 9a, 9b. 



Kellia triangula H. C. Lea, MS., in Coll. Acad. Nat. Sci. Phila. 



Bornia triangula n. sp. ? Dall, 1900, Trans. Wagner Free Inst. Sci., vol. iii, pt. v, 

 p. 1151. 



Description.— ^\\e\\ compact, elevated, triangular; anterior and pos- 

 terior dorsal margins declining at an obtuse angle from the beak; beak 

 distinctly prosocrelous and situated anterior to the middle of the shell; 

 anterior and posterior margins rounded; shell inflated just beneath the 

 beaks but mesially compressed near the basal margin; teeth distinct, shell 

 thin, polished; faint growth lines visible. 



Length, 5 mm.; height, 4.45 mm. 



Occurrence. — Calvert Formation. 3 miles west of Centerville. 



Collection. — Maryland Geological Survey. 



BORNIA MARYLANDICA n. Sp. 



Plate LXXXVIII, Fig. 10. 



Description. — Shell triangular depressed; inflated dorsally; gently 

 compressed mesially near basal margin; beak low, very markedly proso- 



