214 PROCEEDINGS OF THE ACADEMY OF 



Penitella Wilsonii, Conrad, Proc. Acad. Nat. Sc. p. 156, Feb. 1849. Conrad, 

 Journ. Acad. Nat. Sc. 2d ser. i. p. 279, t. 39, f. 4. 



Hab. Lower California. 



Coll. Acad. Nat. Sci. Coll. J. C. Jay. M. D. Coll. G. W. Tryon, Jr. 



This splendid shell may be readily distinguished from the other two species 

 of the subgenus Hatasia by its much larger size. In the form of its cup-shaped 

 appendage it is allied to the following species : 



By a typographical error in Conrad's description of P. Wilsonii in the 

 Journal of the Academy, reference is made to fig. 5 instead of fig. 4 ; this has 

 led Dr. Gray to consider the figure a bad representation of the species, and 

 to mistake the scope intended to be given by Mr, Conrad to the genus 

 Penitella. 



P. quadra, Sowerby. (Sp.) 



Pholas quadra, Sowerby, Zool. Proc. p. 71, 1834. Sowerby, Monog. Pholas, 

 Thes. Conch, ii. p. 499, t. 106, f. 62, 63. Catlow, Conch. Nomenc. 

 p. 4. D'Orbigny, Moll. Voy. Amer. Merid. p. 500. Hanley, Desc. 

 Cat. 4th edit. p. 10. Miiller, Syn. Test. Viv. p. 238. 

 Pholadidea quadra, Gray, Ann. and Mag. 2d ser. viii. p. 385. H. and A. 

 Adams, Genera, ii. p. 329. Fischer, Journ. Conch. 2d ser. iii. p. 51. 

 Hab. Monte Christo. 

 Coll. J. C. Jay, M. D. 



Resembles ,tu bi fe ra very closely, but the posterior appendage is four- 

 lobed, whilst'in tubifera it consists of two reflected lobes; from P. tri- 

 dens it may be distinguished, besides the subgeneric differences, by its 

 anterior dorsal plates being more spread out over the dorsal surface of the 

 shell. 



P. tubifera, Sowerby. (Sp.) 



Pholas tubifera, Sowerby, Proc. Zool. Soc. p. 71, 1834. Sowerby, Monog. 

 Pholas, Tbes. Conch, ii. p. 499, t. 106, f. 64, 65. Adams, Panama 

 Shells, p. 302. Catlow, Conch. Nomenc. p. 4. D'Orbigny, Moll. Voy. 

 Amer. Merid. p. 499. Hanley, Desc. Cat. p. 8. Jay, Cat. 4th edit, 

 p. 10. Muller, Syn. Test. Viv. p. 238. 

 Pholadidea tubifera, Gray, Ann. and Mag. Nat. Hist. 2d ser. viii. p. 3S5. 

 H. and A. Adams, Genera, ii. p. 329. Fischer, Journ. Conchyl. 2d 

 ser. iii. p. 51. 

 Hab. Panama ; West Colombia. 

 Coll. J. C. Jay, M. D. 



Genus Parapholas, Conrad. 



Parapholas, Conrad, Proc. Acad. Nat. Sc. p. 121, Dec. 1848. Journ. Acad. 



Nat. Sc. 2d ser. i. pt. 3, p. 214, and ii. pt. 4, p. 335. Gray, Ann. 



and Mag. Nat. Hist. 2d ser. viii. p. 380. H.-and A. Adams, Genera, ii. 



The genus Penitella has been referred by many authors to the synonymy of 



this genus. Mr. Conrad is almost universally credited with Penitella; which, 



however he merely adopted from Valenciennes, without giving any description 



of its characters. 



Dr. Gray includes the P. p e n i t a of Conrad under a section of Parapholas, 

 described as having a single impressed rib and single posterior umbonal valve; 

 while the other species have two impressed ribs and the posterior dorsal ca- 

 vity divided. 



I have thought it best to restore for this shell the original generic name of 



Penitella. 



P. Californica, Conrad. 



Pholas Californica, Conrad, Journ. Acad. Nat. Sc. vii. p. 236, t. 18, f. 5. 

 Catlow, Conch. Nomenc. p. 3. Hanley, Desc. Cat. p. 8, t. 9, f. 43. 



[April, 



