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ART. XXXIII. — Sijnopsis of the Genera Parapholas and Penicilla. 



By T. A. Conrad. 



Family PHOLADIDjE. 



PARAPHOLAS, Con. 



Anterior and posterior dorsal margins profoundly reflexed with corresponding in- 

 ternal cavities; base with an elongated ventral plate ; cardinal process dilated. 

 Animal inhabiting a tube, which it forms of clay. 



P. Californica, Con. Proceed. Acad. Nat. Sc, Dec. 1848. 



Pholas Californica, Con. Journ. Acad. Nat. Sc, vol. 7, p. 286, pi. 18, fig. 5, 1837. 

 P. Janelli, Desh. Guerin's Mag., 1840, pi. 14, 15, 16. 



Mr. Gray in adopting this genus includes two other shells, which do not appear to 

 me to have the same generic characters, particularly differing in wanting the ventral 

 integument. 



P ENITELL A. Voy. of the Venus. Atlas., 1 846. 



This genus was founded on Pholas penita, Can. ; and the species named P. 

 Conradi, by an author whose name does not appear in the Atlas, the text to which I 

 have not seen, 



P. Conradi. Voy. Ven. Atlas, pi. 24, fig. 1. 

 Pholas penita, Con. 1837, Journ. Acad. Nat. Sc, vol. 7, p. 237, pi. 18, fig. 7. 

 P. concameraia, Desh. 1840, Guerin's Mag. pi. 17, Sowerby, Tiies., sp. 36, p. 197, pi. cvi., fig. 67, 08. 



P. TUBIJERA. Voy. Ven. Atlas, pi. 24, fig. 3. 

 P. XYLOPHAGA, ib. ib. 2. 



P. MELANURA. 



Pholas melamira, Sowerby. Thes. sp. 42, fig. 78, 79. 



Penitella Wilsoni. Con. Journ. Acad. Nat. Sc, vol. 1, 2d series, pi. 89, fig. 4.* 



* Incorrectly referred in the text to fig. 5, and therefore referred by Gray to Parapholas bisukata, Con., instead 

 of Penitella Wilioni, Con. 



