268 SYSTEMATIC PALEONTOLOGY 



FiSSURIDEA MARYLANDICA (C^Jlirad). 



Plate LXIII, Figs. 4a, 4b. 



Fissurella JIarylandica Conrad, 1841, Proc. Acad. Nat. Sci. Phila., vol. i, p. 31. 

 Fissurella Marylandica Conrad, 1843, Jour. Acad. Nat. Sci. Phila., vol. viii, 1st 



ser., p. 187. 

 Fissurella marylandica Conrad, 1843, Proc. Nat. Inst., Bull, ii, pp. 183, 183. 

 Fissurella Marylandica Conrad, 1845, Fossils of the Medial Tertiary, No. 4, p. 79, 



pi. xlv, tig. 1. 

 Fissurella Marylandica Conrad, 1863, Proc. Acad. Nat. Sci. Phila., vol. xiv, p. 570. 

 Fissurella marylandica Meek, 1864, Miocene Check List, Smith. Misc. Coll. (183), 



p. 14. 

 Fissnridea caiilliformis Dall, 1892, Trans. Wagner Free Inst. Sci., vol. iii, pt. ii, 



p. 425. (In part.) 

 Not F. catilliformis Rogers. 

 Fissurella marylandica Harris, 1893, Amer. Jour. Sci., ser. iii, vol. xlv, p. 35. 



Description. — " Elevated, with numerous striae, alternated in size and 

 njinutely granulated b)^ fine crowded concentric lines crossing them ; for- 

 amen large, regularly oval. Length 1 inch. 



" Closely allied to F. Griscomi, but is readily distinguished by a much 

 larger foramen, finer concentric lines, in not being laterally compressed, 

 &c." Conrad, 1841. 



Height, 20 mm. ; length, 43 mm. ; width, 29 mm. 



Occurrence. — Calvert Formation. Plum Point, Chesapeake Beach, 

 Fairhaven. 



Collections. — Maryland Geological Survey, Johns Hopkins University, 

 Philadelphia Academy of Natural Sciences, U. S. National Museum. 



FiSSURIDEA nassula (Conrad). 

 Plate LXIII, Figs. 5a, 5b. 



Fissurella nassula Conrad, 1845, Fossils of the Medial Tertiary, No. 3, p. 78, pi. 



xliv, fig. 6. 

 Fissurella nassula Conrad, 1863, Proc. Acad. Nat. Sci. Phila., vol. xiv, p. 570. 

 Fissurella nassida Meek, 1864, Miocene Check List, Smith. Misc. Coll. (183), p. 14. 

 Fissuridea catilliformis Dall, 1893, Trans. Wagner Free Inst. Sci., vol. iii, pt. ii, 



p. 425. (In part.) 

 Not F. catilliformis Rogers. 



Description. — " Subovate, not elevated ; sides flattened, cancellated 

 with numerous closely-arranged unequal ribs and prominent transverse 

 striae; foramen subovate, rather large ;^ inner margin crenulated.'^ Con- 

 rad, 1845. 



