96 NEW SILURIC GASTROPODS 



The specimens from the Bertie Waterlime clearly represent 

 two species, and it is singular to note that, just as Barrande in 

 describing the first Hercynellas from Bohemia, found a high 

 coned form which he called Pilidion bohemicum and a low coned 

 one which he called P. nobile, and just as Kayser describing the 

 fauna from the Harz found a high spired Hercynella correspond- 

 ing to the former, which he called H . liauchecorni and a low 

 spired one corresponding to the latter, which he called H. beyrichi, 

 so in the Bertie fauna there is one species with a high apex and 

 one which is very flat. 



The Bertie material is very unsatisfactory, for while the form 

 of the shell is well preserved, the details of surface markings are 

 indistinct and a precise description is therefore impossible. The 

 shell was apparently very thin and may have been only slightly 

 impregnated with lime or even entirely corneous, for which 

 reason it is to be expected that the shell would be more or less 

 macerated. Some portions would remain in place, but others 

 would stick to the mud in which the shell was buried, and, 

 fossilized, would appear now in the mold. Thus little patches 

 of shell are visible on both mold and relief, and since the shell is 

 so thin that it leaves little more than a black film of organic matter 

 on the rock, the difficulties in making observations on growth 

 lines, striae and so forth are obvious. There is no way of 

 orienting the shell, since the internal features are not visible, and 

 since in the better preserved material of Bohemia it has been 

 observed that the position of the sinus is variable. We may, 

 therefore, for convenience sake speak of the right and left, and 

 posterior and anterior portions of the shell with reference to a 

 line of symmetry drawn through the sinus, which is placed 

 anteriorly and the figures throughout the paper will be oriented 

 in this way and referred to accordingly. 



Hercynella buffaloensis sp. nov. 



Description: — Shell patelliform, sub-circular, non-spiral. 

 The beak is destroyed, but its position would be asymmetric, the 

 shell showing an abrupt drop on the right side (see pi. I fig. l) 

 and a gentle slope on the left. Growth lines are clearly visible 

 on most of the shell, being particularly strong at the margin. 

 The growth lines show strong incurving with the formation of a 

 peripheral sinus. A few fine striae are faintly indicated to the 



