590 REPORT— 1863. 



Tapes diversum, Sby. [=ra/7es staminea, Conr., var. Prfiftt, 

 Desh. ] Recent formation. San Pedro. 



Saxicava abrupta, Com*., n.s. [Probably the shortened form of 

 Petricola carditoules, Conr.] Recent formation. San Pedro. 



Petricola Pedroana, Conr., n.s. [Allied to P. ventricusa, Desh. J 

 Recent formation San Pedro. 



Schizothcerus Nuttalli, Conr., " n.s."= Trestis capax, Gld. Recent 

 formation. San Pedro. 



?Liifrana Traskei, Conr., n.s. [Not improbably = Saxidomus 

 Nidtallii, Conr., jun.] PMiocene. Carmello. 



Madra Dieyoana, Conr., n.s. Like M. cdbaria, of the Oregon 

 Miocene. [Resembles Mulinia angtdata, Gray.] ? Miocene. 

 San Diego. 

 35. 32. Modiola contracta, Conr., n.s. [Very like 3/. rfcte, Conr.] ? Mio- 

 cene. Monterey Co. Recent formation. 



Mytdm Pedroanus, Conr., n.s. [Probably=3f. edulis, jun.] 

 Recent formation. San Pedro. 



Pecten Deserti, Conr., n.s. [Resembles P. circularis.'] Mio- 

 cene. Carrizo Creek, Colorado Desert. 



Anoinia snbostafa, Conr., n.s. [? = Plactmanomia macroschisma.^ 

 Miocene. Colorado Desert. Allied to A. liuffini. 



Ostrea vespertina, Conr., n.s. [Resembles O. lurida, var.] Mio- 

 cene. Colorado Desert. Like O. suhfalcata, Conr. 



Ostrea Heermanni, Conr., n.s. Colorado Desert. 



Peiiitella spel(va, Conr., n.s.* Recent formation. San Pedro. 



Fissurella cremilata, Sby. [^ = Lucapma c] Recent formation. 

 San Pedro. 



Crepidtda princeps, Conr., n.s. [= C grandis, Midd.] Recent 

 formation. Santa Barbara. 



Narica Diegoana, Conr., n.s. ? Miocene. San Diego. 



TroeMta Diegoana,Conx., n.s. [Like T. ventricosa ; but may be 

 GaUnis contortus.'] PMiocene. San Diego. 



Crucihulmn spinosum, Conr., n.s.t Recent formation. San Diego. 



Nassa interstriata, Conr., n.s. [=iV. metidica, Gld.]. Recent 

 formation. San Pedro. 



Kasm Pedroana, Conr., n.s. [Comp. Atnycla gatisapata and its 

 congeners.] J Recent formation. San Pedro. 



Sfrephoiia Pedroana, Conr., n.a. [Comp. Olimlla bcetica.'] Recent 

 formation. San Pedro. 



Litorina Pedroana, Com:, n.s. [ = L. plena, G\di.'\ Recent forma- 

 tion. San Pedro. 



Strammnfa petrosa, Conr., n.s. [Is perhaps Monoceros lugnbre.'] 

 ?—. Tulare Valley. 



* Mr. Conrad regards the " coriaceous cup as characteristic of the genus." It appears 

 a subgenus of Pholadidea, differing m the form ot the plate. Mr. Tryou, " Men. Pho- 

 lad.," p. 66, restricts it to the Penitella penita, which (according to his diagnosis) has 

 one central and two anterior dorsal plates. The closely related P. ovoidea he leaves in 

 the original genus, as having "two dorsal accessory valves," although he allows that "its 

 position cannot be accurately determined on account of the loss of its dorsal valves." 

 Conrad's fossil has the shape of P. ovoidea ; but although he says that it is " widely dis- 

 tinct" from P. penita, I am unable to separate it from the ovoid form of that species, 

 which will be i'ound in the Smithsonian series. 



t This is certainly Sowerby's species, to which Conrad gives a doubting reference. In 

 the text he gives it as ^'■spinosum, Conr.," in his table marking it as " nov. sp." 



+ Conrad compares N. interstriata to N. trivittata,^Siy , and N. Pedroana ioN. lunatd, 

 Sav.and states that the two Atlantic species are "associated with each other both in the sea 

 and in the Miocene deposits of Virginia and Maryland." As the two correlative species 

 sre fo'ind together, living and fossil, on the PaciHc side, there is presumptive evidence for 

 their havuig descended from a couuiion stock. 



76 



