358 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxvi. 



This is Ckiona Morch, 1853, and of Roiiier, 1857; Chroi/ij)halus 

 Adams, 1857; and Omphaloelathrmn Trj^on, 1884, not Morch, 1853. 

 It is not Chion Scopoli, 1777; 6%/wv /.s Forster, 1788; Oh! one Desvoidy, 

 Di]}fera^ 1830; Chionca Dalman, 1810; nor Chio)tc Gray, 1838, Iiv^a 

 few of the liirger species like C. g7iidia^ a feeble fourth cardinal is 

 sometimes present in the right valve l)elow the ligament; and the right 

 posterior dorsal margin behind the ligament is sometimes grooved to 

 receive the beveled edge of the opposite valve. In Gomphina alone 

 have 1 found any anterior grooving of the margin in the left valve. 

 The siphons are separate and short, the cardinals entire or feebly 

 channeled. 



Section Chione s. s. (See above.) 



Section Timoclea Brown, 1827. Tj^pe, Venus ovata Pennant. 



Sculpture predominantly radial, the concentric element feeble, the 

 escutcheon smooth; the middle left and two posterior right cardinal 

 teeth grooved. 



This is P^/^i/^Affe-' Leach, 1852, notRisso, 1826; Leukoma Roira^v, 1857, 

 and Leucoind Sto\\Q.7AvA, 1871, not of Stephens, 1829; Oyfherea^. and 

 A. Adams, 1857, not of Bolten, 17l»<; Marcia (part) Romer, 1857, not 

 of Koch, 1835. 



Section Olaumnella Gray, 1851. Type, Venuf< fasciata Da Costa. 



Sculpture of broad concentric waves and fine concentric stria^, the 

 radials obsolete; the waves not pinched out behind; the ligament 

 covered by the margin of the valves when closed. 



This is Zuclelca Leach, 1852. 



Section Liroj)hora Conrad, 1864. Type, Ve^uis athleta Conrad; a 

 recent species is F. papkia Linnaeus. 



Sculpture of broad concentric waves, attenuated and often conspicu- 

 ously lamellose distally; radiall}' striate; ligament exposed; the edges 

 of the right nymph and posterior left cardinal with interlocking rugos- 

 ities. 



This is Clausina Romer, 1857, not of Brown, 1827; Anaitis {paphia) 

 Fischer, 1887, not of Tryon. 1884; and Anaitk (part) Romer, 1857, 

 not A)iaiti>i Duponchel, 1829. 



? Section Vohipia Def ranee, 1829. Type, V. rugosa Def ranee. Eocene 

 of Hauteville. 



Shell small, sculpture superficially resembling Lirophora^ })ut with 

 lunule and posterior area defined ])y a deep sulcus dividing the disk 

 into three areas crossed by thick, swollen, concentric ribs; beaks high 

 and curved; hinge of three teeth, of which one is bifid; pallial line not 

 sinuated ? 



In placing this shell here I have followed Fischer, since the species 

 has not been well figured and the descriptions given of it are far from 

 clear. I have not been able to obtain specimens for examination. 

 From the very obscure figure of Defrance 1 should have suspected 



