(G.) 



NOTES ON SOME NEW OR IMPERFECTLY KNOWN FORMS AMONG 

 THE BRACHIOPODA, ETC.* 



By JAMES HALL. 



In the preparation of a supplementary part to Vol. IV, of the 

 Palceontology of New Yorh, it became necessary to re-examine many 

 of the genera and species more critically than I had before been able 

 to do. On every side, it is evident that we are far from a complete 

 knowledge of those forms which have been longest known, while it is 

 to be expected that every year will give ns new and important facts 

 regarding those which have been less studied. 



It has been asserted and believed that the genus Lingula, as known 

 in the living forms, was the first among the marine inhabitants of our 

 globe. Examples have been cited from the Potsdam sandstone of 

 America, and from the old Lingula flags of Europe ; and some little 

 time since it might have been considered very heretical to doubt the 

 combined authority on which such statements are made. However, 

 when we come to examine the evidence advanced in support of such an 

 assertion, we find it, even at this day, far from satisfactory. The living 

 Lingula is a shell, generally of an elliptical or spatulate form, living 

 more usually in sandy deposits, but occurring in all others. 



In the older sandstones and limestones we find fossils having phos- 

 phatic shells, of the form of Lingula, but of the relations or identity 

 of internal structures we know little or almost nothing. In fjict, the 

 fossil linguloid shells are among the most difiieult to separate from their 

 matrix ; the interior of the shell is rarely seen, aud for the most part 

 still remains unknown. 



Some years since (in 1865), Mr. Salter proposed the name Lixgulella 

 for some of the Linguloid shells of the Silurian rocks of Great Britain, 

 and one of his species {L. ferruginea) is regarded as the earliest Brach- 

 iopod hitherto discovered in England. 



In 1803 I described some fossils from the Potsdam sandstone of the 

 Mississippi valley as Lingula aurora and L. aurora var., pointing out 

 a peculiar texture of the shell, and indicating in one of them an ine- 

 quality of the valves. These forms correspond with Lingilei.la of 

 Salter, and will be described and illustrated as Lingulella aurora, etc. 



* Published March, 1871. Reprinted with exphmiition of figures, March, 1872. 



