210 



The aiiimal forms a tube of indurated clay, represented at f. 6 

 ( 7, err. typ.), extending nearly to the surface of the bed in which it 

 burrows. 



2. Parapholas penita, Conr. 



Pholas penita, Joum. p. 237. pi. 18. f. 7. 



Parapholas penita, Conr. Journ. 1849. 



= Pkolas concamerata, Desh. Rev. Zool. 1839. 



Hab. Sta. Barbara, una cum P. Californica. Mus. Gould, Jay. 



Is much smaller than P. Californica ; without an internal callus 

 at the posterior hinge margin ; and with a differently shaped apo- 

 physis. 



Subgenus Platyodon, Conr. 



Testą Myae sitnili, sed dente cardinali tninus prominente, magis 

 dilatata ; linea p)o.llii sinu antlce angusto, postice profundo. 

 Animal siphonibus duahus haud divergentibus, valvulis quatuor 

 testaceis extremitate8 claudentibus. 



3. Platyodon cancellata, Conr. Joum. p. 236. pi. 18. f. 2 ; 

 H. & A. Ad. Gen. vol. ii. p. 354. 



Hab. Sta. Barbara ; inter paludes limosas, et rupes. Mus. Nutt., 

 Brit., Jay. 



Subgenus Cryptodon, Conr. 



Testą Lutrarise simili, sed margine cardinali profunde canalicu- 

 lato. Animal siphonibus duabus haud divergentibus, valvulis 

 corneis duabus extreniitates claudentibus. 



4. Cryptodon Nuttallii, Conr. Journ. p. 235. pi. 18. f. 1. — 

 (Non Mactra Nuttallii, Reeve, Conch. Ic.pl. 21. sp. 125.) 



Hab. Sta. Barbara, in paludes, inter fluxum maris. Mus. Nutt. 

 1 =Cgpricia Nuttallii, quasi Conr. B. M. 



5. SpHiENiA Californica, Conr. Joum. p. 234. pi. 17. f. 11. 

 (1834). 



=zCryptomya Californica, Conr. loc. cit. 1849, p. 208 ; H. & A. 

 Ad. Gen. vol. ii. p. 359. 



Hab. Sta. Barbara, inter paludes, infrequens. Mus. Nutt,, Jay. 



Conrad describes the pallial line as " without a sinus, but fonning 

 a right angle posteriorly ;" in Mr. Nuttall's specimen, however, the 

 siuus may be traced, though very faintly marked. 



— 6. Thracia ctjrta, Conr. joura. p. 248. pi. 19. f. 8. 



Hab. Sta. Barbara. Mus. Nuttall. 



A fine pair (not a single valve only, as stated by Conrad) is in 

 Mr. Nuttall's cabinet. It is remarkable for its great squareness at 

 the posterior end. 



