304 SYSTEMATIC PALEONTOLOGY 



Family VENERID/E. 

 Subfamily VENERIN/E. 

 Genus VENUS (Linne) Lamarck. 



Venus ducatelli Conrad. 

 Plate LXXV, Figs. 7, 8. 



Venus Ducatelli Conrad, 18;-)8, Fossils of tbe Medial TerLiary, p. 8, pi. iv, fig. 2. 

 Venus Ducatellii Conrad, 1863, Proc. Acad. Nat. Sci. Phila., vol. xiv, p. 574:. 

 Venus Bucatellii Meek, 1864, Miocene Check List, Smith. Misc. Coll. (183), p. 9. 

 Vemts Ducateli Whitfield, 1894, Mon. xxiv, U. S. Geol. Survey, p. 67 (in part), 



pi. xi, figs. 1-3. 

 Venus Ducateli Dall, 1903, Trans. Wagner Free lust. Sci., vol. iii, pt. vi, p. 1309. 



Descripiion. — " Shell suborbiciilar, convex, thick; disks with numerous 

 approximate, recurved ribs, laminar and much elevated towards the pos- 

 terior margin ; extremity obtuse ; beaks distant from the anterior margin ; 

 umbo not inflated; lunule defined by an impressed line, not very pro- 

 found; posterior margin rectilinear; two of the cardinal teeth in the left 

 valve remote, thick, bifid; anterior tooth much compressed. 



" This shell is related to V. Mortoni, but is much smaller, less ventri- 

 cose, and has more prominent ribs. It is obtained in fragments only, 

 but those are abundant. It is named in compliment to the state Geol- 

 ogist of Maryland, Professor Ducatel.^' Conrad, 1838. 



Length, 70 mm. ; height, 56 mm. ; diameter, 20 mm. 



Occurrence. — Calvert Formation. Church Hill. 



Collections. — Maryland Geological Survey, Johns Hopkins University. 



Venus rileyi Conrad. 

 Plate LXXVI, Figs. 4, 5. 



Venus Rileyi Conrad, 1838, Fossils of the Medial Tertiary, p. 9, pi. vi, tig. 1. 

 Vemis Eileyi Tuomey and Holmes, 1856, Pleioceue Fossils of South Carolina, p. 78, 



pi. xxi, fig. 8. 

 Venus Rileyi Emmons, 1858, Rept. N. C. Geol. Survey, p. 293. 

 Mercennria Rileyi Conrad, 1863, Proc. Acad. Nat. Sci. Phila., vol. xiv, p. 574. 

 3[ercenaria Rileyi Meek, 1864, Miocene Check List, Smith. Misc. Coll. (183), p. 9. 

 Venus tridacnoides var. Rileyi Dall, 1903, Trans. Wagner Free Inst. Sci., vol. iii, 



pt. vi, pp. 1310, 1311. 



Description. — " Shell obliquely ovate, slightly ventricose, thick, very 

 inequilateral ; disks with small crowded reflected concentric ribs ; anterior 



