NATURAL SCIENCES OF PHILADELPHIA. 18T 



interior seen in our shell and the type of Lingulella; and so far as 

 I have been able to determine, from examining casts of Lingu- 

 lepis, they do not appear to have possessed a false area with a 

 furrow for the peduncle, seen in the shell under consideration and 

 in Mr. Salter's type. 



Compared with Mr. Salter's tj'pe (L. Davisii), as illustrated by 

 Mr. Davidson, our shell will be readily distinguished specifically, 

 by its much smaller size, proportionally shorter form, more 

 pointed beak, and less straightened latei-al margins. The inte- 

 rior of its ventral valve also shows no traces of a small ridge 

 indicated by a linear furrow in the internal casts of Mr. Salter's 

 sijecies. 



Locality and position. The specimens were discovered by 

 Robert H. Lamborn, Esq. (after whom I have named the spe- 

 cies), in a thin bead of shale between two beds of limestone 

 bearing heavy dejjosits of galena, at Mine La Motte, Madison 

 Co., Missouri. They were sent b}^ that gentleman to Prof. Leidy, 

 of Philadelphia, and by him referred to me for study. I am not 

 acquainted with the age of the rocks at Mine La Motte, never 

 having seen any other fossils from there, but from the affinities 

 of this single fossil to Lingulella from the Lingula flags of Wales, 

 and to Lingulepis from the Potsdam sandstone of Minnesota, it 

 would seem that these lead deposits belong to a much older 

 period than the Galena and Dubuque lead-bearing limestone, of 

 Illinois and Iowa, although the latter is known to belong to the 

 Lower Silurian. 



18T1.] 



