OF CONCHOLOGY. 219 



43. Unio pernodosuf!, hoa.. Two specimens. It is apparently a 



good species. 



44. " pcrplexus, Lea. 



45. " perradiatus, Lea. Retained in deference to Mr. 



Wheatley. (See multiradiatus). 



46. " phaseohis, Hildreth. 



47. " plenus, Lea. 



48. " propinquus, Lea. Abundant. 



40. " pudicus, Lea. The young shells appear to me to be 

 pudicus ; the mature ones bear a strong resemblance 

 to U. Lyonii^ Lea. My determination is question- 

 able 



50. *' pusfulosus, Lea. 



51. " PyhasiL Lea. Occurs also in small streams, 



52. " Ravenelianus, Lea. A single specimen. May not be 



correctly determined. 



53. " rectus, Liim. 



54. " securis. Lea. 



55. " sparsus, Lea A single well chai-acterized specimen. 



56. " Stetvardsofiii, Lea. 



57. " siibtentiis, Say. 



58. " tenici'ssimus, Lea. 



59. " tesserulce Lea. A single immature shell ; determina- 



tion questionable. 



60. " triangularis, Barnes. 



61. " tuberosus, Lea. Occurs in the Holston, Clinch and 



Tennessee Rivers with a more inflated form than ia 

 seen in typical specimens. 



62. " midalatus, Barnes. 



63. " varicosus, Lea. 



64. " verrucosus, Barnes. 



65. Margaritana dehiscens, Say. Rare. 

 QQ. "' marginata, Say. 



67. " rugosa, Bar. Rare. 



68. Anodonta ohlita ? Lea. A single small specimen. Deter- 



mination doubtful. 



Univalves, (in alphabetical order). 



69. Anculosa Cincinnatiensis, Lea. In presenting my opin- 

 ions on the species I am now considering, it may be well to pre- 

 mise that I began the study of the Strepomatidse of the Holston 

 River strongly impressed with the correctness of Mr. Tryon's 

 determinations and synonymy, and with a desire to profit by his 

 then unquestioned advantages. After a very thorough study of 

 an immense number of specimens, of different ages and varieties, 

 I arrived at results which are as follow : 



