116 BULLETIN 90, UNITED STATES NATIONAL MUSEUM. 



It has been assumed, since there are no obvious discrepancies, that 

 the two valves figured belong to the same species, though collected 

 by different persons and at different times. 



Order PRIONODESMACEA. 



Superfamily NUCULACEA. 



Family NUCULIDAE. 

 Genus NUCULA Lamarck. 



Nuciila Lamarck, Prodrome Nouv. Class. Coq., p. 87, 1799. Type, Area 



nucleus Linnaeus. 

 Nuculana Link, Bescbr. Rostock Samml., p. 155. 1S07 (modification of 



Lamarck's name to suit the taste of Link). 

 Olycymens Da Costa, Brit. Concli., p. 170, 1778, part. 



The name Nuculana^ by some writers erroneously utilized for the 

 group first discriminated by Schumacher under the nam^e of Leda^ 

 was proposed by Link as a more desirable form of the name Nucula, 

 proposed by Lamarck for shells of the type of Area nucleus Linnaeus, 



Link changed many names to suit his own fancy, and in the pres- 

 ent case Nuculana is simply an exact sjmonym of Nucula. 



NUCULA TAMPAE, new species. 



Plate 21, figs. 13, 14. 



Shell small,- rounded trigonal, solid, very inequilateral ; beaks low, 

 adjacent; anterior end produced, rounded, with the dorsal margin 

 flattened, but no circumscribed lunule ; posterior end short, subtrun- 

 cate, with a flattened ill-defined area, but no distinct escutcheon; 

 ligament rather large for the size of the shell and situated internally 

 directly behind the beaks; surface concentrically finely rugose, the 

 sculi)ture crossed by fine radial striae, Avith wider interspaces (too 

 fine to be shown in the figures) ; margins finely crenulate internally. 

 Length 7.3 mm., height 6 mm., maximum diameter 4.75 mm. 



Tampa silex beds. Ballast Point, Tampa Bay, Florida. Collected 

 by Dall, Burns, and Post. Type-specimen U. S. Nat. Mus. No. 

 165169, from the Post collection. 



The sculpture in some of the pseudomorphs is so faint that the 



valves appear nearly smooth, but this is probably only an incident of 



fossilization. 



Family LEDIDAE. 



Genus LEDA Schumacher. 



Leda Schumacher, Essai, pp. 55, 172, 1817.— DAll, Trans. Wagner Inst, 

 vol. 3, pt. 4, p. 579, 1898. Type, Leda rostra t a Gmelin (not Mon- 

 tagu) =il/?/a pemula Muller, Zool. Dauica, 1779. 



