34 DAVENPORT VCADEMY OF NATURAL SCIENCES. 



This species is placed in Hydrobia because I do not know what 

 other disposition to make of it. It is, perhaps, congeneric with such 

 species as Amnicola floridana Frauenfeld,* which has a more acute 

 apex than Bythinella, and is slenderer than Amnicola. 



Note on Pyrgulopsis spinosus Call & Pilsbry. 



I find that this species has no affinity with the other shells in- 

 cluded under Pyrgulopsis. Its position seems to be in Potamopyrgus 

 or in an as yet undefined genus. Pyrgulopsis C. ec P. is, perhaps, in 

 characters of shell, not separable from Lyrodes of Doering, the 

 description of which I had not seen at the time Pyrgulopsis was pro- 

 posed. A thorough examination of the anatomy of these snails, and 

 comparisons with that of Pyrgula s. s., must be made before the true 

 value of all these groups can be determined. To facilitate compari- 

 sons by those who do not have access to the publications containing 

 Mr. Doering's papers on mollusca, I copy here his diagnosis of 

 Lyrodes :\ 



Testa subperforata elongata, ovato-conica, tenuis, hyalina, carinala, saepius acu- 

 leata, vel spiraliter lineata. 



Animal pede oblongo, antice sublyrce-formi, lobis duo in corpore retractilihus; 

 post ice lanceolato; tentaculis subconicis, baculiformibus; rostro brevi. 



The type is L. guaranitica Doer. The old species Paludeslrina 

 andecola D'Orb., included by Stimpson in Pyrgula, and Paludina cor- 

 onata Pfr., are placed by Doering in the group. The animal resem- 

 bles Pyrgula bicarinata as described by Moquin-Tandon in external 

 characters, the foot being bluntly bilobed before — not distinctly au- 

 riculated, as in Bythinella, Amnicola, and other genera. 



* Hydrobia wetkerbyi is probably a iiillia. 



-(■Bole-tin de la Acidemia Nacional de Ciemias en Cordoba, Tomo VI!., 1SS5, p. |6l : L^uav 

 anitica figured on p. 463. 



