MARYLAND GEOLOGICAL SURVEY 681 



Genus ANTIGONA Schumacher 1 

 [Essai, 1817, pp. 51, 154] 



Type. Antigona lamellaria Schumacher. 



" Shell smaller and more trigonal, less rotund than Cytherea s. s. ; the 

 left anterior lateral lamellifonn and larger, with a perceptible socket in 

 the right valve ; the posterior right cardinal broad and deeply bifid ; pal- 

 lia! sinus small, triangular." Ball, 1903. 2 



Subgenus APHRODINA Conrad 

 [Am. Jour. Conch., vol. iv, 1869, p. 246] 



Type. Meretrix tippana Conrad. 



" Shell rounded or suboval, striated or sulcated ; hinge in the left valve 

 with three diverging cardinal teeth, the anterior tooth as thick as the 

 middle one or thicker, and a straight, compressed, transversely rugose 

 lateral tooth parallel with the margin of the shell above it; pallial sinus 

 deep, and similar to that in Caryatis Boemer." Conrad. 1868. 



" Shell concentrically striated, with a circumscribed lunule, but no 

 defined escutcheon; inner margins smooth; pallial sinus ample, free, 

 ascending, rather rounded in front; hinge with three cardinals in each 

 valve, the right posterior cardinal bifid ; an elongate anterior lateral cor- 

 rugated on both sides and received into a corrugated pit in the right valve ; 

 nymphs plain." Ball, 1903. 3 



ANTIGONA (APHRODINA) TIPPANA Conrad 

 Plate XL, Figs. 3, 4 



Meretrix tippana Conrad, 1858, Jour. Acad. Nat. Sci., Phila., 2d ser., vol. 



iii, p. 326, pi. xxxiv, fig. 18. 

 Dione tippana Meek, 1864, Check List Inv. Fossils, N. A., Cret. and Jur., 



p. 13.. 



Etymology: Antigone, daughter to CEdipus. 



1 Cytherea Bolten, 1798, (part) Mus. Boltenianum, ed. i, p. 177; 1819, ed. ii, 

 p. 124. Venus puerpera Linnaeus. Not Cytherea Fabricius (Diptera), 1795, 

 Lamarck, 1806, nor H. and A. Adams, 1856. 



Callista Fischer, 1887, Man. de Conch., p. 1084. Venus verrucosa Linn6. 

 Not Callista Morch, 1853. 



2 Trans. Wagner Free Inst. Sci., Phila., vol. iii, pt. vi, p. 1273. 



3 Trans. Wagner Free Inst. Sci., Phila., vol. iii, pt. vi, p. 1272. 



