60 THE NAUTILUS. 



THE NOMENCLATURE AND SYSTEMATIC POSITIONS OF SOME NORTH 

 AMERICAN FOSSIL AND RECENT MOLLTTSKS. 



BY JUNIUS HENDERSON. 



Pholadomya undata Meek and Hay den (Proc. Acad. Nat. ScL, 

 Phila., VIII, 1856, p. 81), now generally known as Liopistha. 

 (Cymella) undata, Cretaceous, Rocky Mountain region, is pre- 

 occupied by P. undata Dana (Wilkes U. S. Expl. Exped., X, 

 1849, p. 687, Atlas, PI. 2, figs. 11, 11 a, lib), Carboniferous, 

 Australia. It is unfortunate to have to abandon Meek and 

 Hayden's name for the well-known American species, but the 

 rules of nomenclature require it, so I propose the name Liopistha 

 ( Cymella) montanensis, in reference to both the type locality and 

 the geological group from which it was described. 



Anodonta parallela White, was described from the Cretaceous 

 of Colorado in 1878 (Hayden Survey, IV, p. 709). Binney 

 used the same name in his Bibliography of North American 

 Conchology, Pt. I. 1863, p. 46, citing Ferussac, "Hyde, in 

 litt." As neither Ferussac nor Binney, so far as I know, ever 

 published any description to accompany that name, White's 

 name will stand. 



Unio rectoides White, Tertiary, Utah (U. S. Geol. Surv., Bull. 

 34, 1886, pp. 11, 15, 21), is preoccupied by U. rectoides Whit- 

 field, "Cretaceous," New Jersey (U. S, Geol. Surv., Monog. , 

 Vol. 9, 1885, pp. 250, 258). As Pilsbry and others have 

 shown, Whitfield'srectoide-s' is itself a synonym of Lampsilis recta 

 (Lam.), and is from Quaternary deposits, instead of Cretaceous. 

 Under the circumstances it seems too bad to abandon White's 

 name, but the rules adopted in the interest of ultimate stability 

 of nomenclature require it. I propose for it the name Unio 

 whitei. It should likely be removed to some other genus. 



Unio broivni Whitfield, Cretaceous, Montana (Bull. Am. Mus. 

 Nat. Hist., XIX, 1903, p. 485), is preoccupied by U. bronmii 

 Lea, recent, Asia (Proc. Acad. Nat. Sci., VIII, 1856, p. 95), 

 so Pilsbry renamed it Parreysia barnumi (NAUTILUS, XVIII, 

 1904, p. 12), a fact that seems to have been overlooked by sub- 

 sequent writers, which is likely to be the case where new names 



