BlacTc Shale of Eastern Kentucky. 387 



Lingulipora — new subgenus. 



The character upon which this proposed subgenus of Lingula 

 is based has not been unnoticed. Hall and Clarke in 1892 

 (Pal. New York, vol. viii, pt. 1, p. 17) mention it as occurring in 

 the very species described below as new under the name of L. 

 Williamsana, in which, indeed, it is a striking character of the 

 shell. Similarly record is made in the same connection of "a 

 finely preserved specimen of an undetermined species from the 

 Waverly sandstone of Pierrepont, Ohio," which " shows strong 

 punctse, visible to the naked eye on the internal surface, where, 

 according to the author above cited, the calcareous layers of 

 the test are thickest." These authors are inclined to regard 

 this punctation as an exaggeration of the microscopic canals 

 which Gratiolet has described as occurring in the calcareous 

 layers of the shell of Lingula anatina (Journal de Conchylio- 

 logie, 2nd ser., vol. viii, 1860, p. 59). The figure given by 

 Hall and Clarke (after Davidson after Gratiolet) show the 

 tenuous shell as consisting, in the instance given, of at least six- 

 teen alternating layers of calcareous and corneous matter. Each 

 one of these must accordingly have been very thin, and to 

 find in such attenuated sheets punctse of a size to be detected 

 by the naked eye and which at the same time are, as peculiar 

 to each corneous layer, discontinuous, while not at all impossi- 

 ble would be, I think improbable. In the type species Lin- 

 gula {Lingulipora) Williamsana the punctse are visible upon 

 exfoliate surfaces, upon the inside and also upon the outside of 

 the shell. There is nothing to lead to the supposition that they 

 are not practically continuous through the shell, and it is my 

 belief that they are so. With pores the size of those in L. 

 Williamsana and with the laminae as thin as they must be in 

 a small shell like that, it would be expected that in exfoliated 

 surfaces not only the punctae of the shell layer so exposed 

 would be visible, but also less distinctly those of the next 

 punctate layer below showing through. This, however, does 

 not seem to be the case. 



A large number of Lingulas representing many species and 

 many geological periods have been examined with a view to 

 ascertain to what extent this character of punctation has been 

 developed in the genus during Paleozoic time. It seems to be 

 by no means a frequent character and to vary considerably in 

 degree, from where it can be seen with the naked eye as 

 described by Hall and Clarke, to where it is difficult to catch even 

 with an ordinary hand lens. In point of range the character 

 seems to be restricted to late Paleozoic time, and not to appear 

 in allLinguloid shells even then. In the Lingulas of the earlier 

 Paleozoic, just as in recent Lingulas, not the faintest trace of 



