134 Remarks on Certain Species of N. A. HeliGidoe. 



se deroule par line spire plus large que ceux qui le precedent. Les 

 tours de spire au nombre de sept sont convexes, couverts de strics fines, 

 regulieres, rapprochees, plus profondes sur le cote superieur que dans la 

 partie ombilicale : elles s'attenuent insensiblement en passant du dessus 

 a la circonference et de la circonference au-dessous. L'ouverture est 

 tres oblique, le bord droit, epaissi en dedans, est renverse en deliors ; il 

 se continue par ses extremites en un bord gauche, sur le milieu duquel 

 se releve une petite dent oblique et courbee que Ton voit tout entiere 

 en dehors lorsque I'on regarde l'ouverture de profil. Cette coquille est 

 d'un blanc grisatre, et elle est ornee de flamraules longitudinales, etroites, 

 irregulierement distribuees et d'un brun pale et rougeatre. 

 "Elle a 10 mill, de diametre et 4 de hauteur."* 



Pfeiffer (Mem. i. p. 409, 1848) assigns H. miorodonta to the 

 Bermudas and Texas, " teste coll. Menkeana." 



Miihlfeldt and Desliayes did not know the localities from 

 which their specimens came — the figure and description of the 

 former author are unsatisfactory, and the latter described from 

 a single individual, and gives a figure which is by no means 

 conclusive. Under such circumstances, considering that the 

 species of the group to which H. cereolus and 11. microdonta 

 belong are very variable, it is not surprising that difficulty 

 should be now experienced in determining them. 



When in Bermuda, in 1852, I collected a large number 

 of specimens of a finely striated shell, pretty closely agreeing 

 with the description of H. micTodonta Desk. ; but Mr. 

 Shuttleworth, in 1855, was disposed to think it distinct, and 

 proposed to call it H. delitescens, under which name it has 

 been extensively distributed, but nothing published about it. 



In 1853, Mr. S. sent me specimens labelled " H. inicrodonta 

 Desh., Key "West, Florida," which difi'er very much from the 

 Bermuda shell, having sharp and more distant striae, and 

 an internal lamella. I also received from the same source 

 examples of II. volvoxis Parr., from Ilopeton, Ga. Both these 



* See facsimile of the figure to which Deshayes refers, in W. G. Binney's Supp. 

 to the Terr. Moll., pi. 78, fig. 23. 



