29 DR. P. P. CARPENTER ON THE SHELLS OF PANAMA. 



M. 152, in having a yellow, not silky, epidermis. The specimens 

 vary considerably in thickness. The genus scarcely differs from 

 Miltha. 



453. Capsa altiorIphigenia a., M. 69. 



454. Donax assimilis y M. 74. 



455. Donax gracilis. Stet. 



456. Donax navicula, M. 77. 



457. Donax rostratus. This single valve proves to be the true 

 D. carinatus, M. 71, and not the shell which I called D. culminatus, 

 M. 72 ( = carinatus, var., Hani, in Mus. Cum.), which I subse- 

 quently affiliated to the supposed rostratus, Maz. Cat. p. 548, on the 

 authority of Dr. Gould's specimen. We were probably both misled 

 by the " very sharp angle," which (as compared with the other form) 

 I should call rounded, and the "concave" surface, which I should 

 translate into flat. The names have been altered in the Cumingian 

 collection since the Mazatlan shells were identified ; but Mr. Hanley 

 informs me that they are now correct; that the D. culminatus, M. 

 72, is his own original carinatus; and that the D. carinatus, M. 71 

 (olim Mus. Cum.), which is certainly D. rostratus, P. 457, must 

 stand under Prof. Adams's name. 



458. Tellina aurora. Stet. 



459. Tellina cognata, C. B. kd.=zPsammobia casta, Rve., teste 

 Cuming. The sculpture consists of semidiagonal striae passing over 

 the lines of growth. In other specimens examined from Panama 

 these are sometimes crowded, sometimes distant, occasionally flex- 

 uous, sometimes almost evanescent. 



460. Tellina columbiensis. (Peroncea.) 



461. Tellina concinna=Macoma c. The "slight tinge of pink" 

 I could not discover. 



462. Tellina crystallinaTellidora c. 



463. Tellina cumingii, M. 55. 



464. Tellina dombeyi=Macoma d., M. 50. 



465. Tellina felix, M. 51. (Angulus.) 



466. Tellina laceridens. (Peron&oderma.) 



467. Tellina pror a. (Peronceoderma.) 



468. Tellina puella. Not unlike T. felix, and distinct from M. 59. 



469. Tellina rubescens. (Perontcoderma.) 



470. Tellina siliqua. The two odd valves belong probably to a 

 Ma coma, in shape resembling Thracia phaseolina. 



471. Tellina simulans=T. (Peronceoderm a) punicea, M. 54. The 

 species was described, for geographical reasons, from a young, pale, 

 and undeveloped valve. On comparing it with the Protestor's ov\u 

 West Indiau specimens, I could detect no difference. 



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