.4.. 



TH E 



AMERICAN JOURNAL OF SCIENCE 



[FOURTH SERIES.] 



Art. X. — Tamiobatis veiustus • a new Form of Fossil 

 Skate ; by C. R. Eastman. With Plate I. 



Through the kindness of Mr. F. A. Lucas, of the United 

 States National Museum, the writer has enjoyed the oppor- 

 tunity of studying a remarkable fossil belonging to the collec- 

 tion under the charge of this gentleman. The specimen 

 (Nat. Mus. Cat. No. 1717) was identified by Mr. Lucas as "the 

 skull of a fossil skate," and is shown by the records to have 

 been found in the eastern part of Powell County, Kentucky. 

 Unfortunately, the exact horizon from which it was obtained 

 is not affirmed by the original memoranda accompanying the 

 specimen, but its history seems to leave no doubt that it was 

 derived from rocks occurring in situ in that part of Kentucky. 



Characters of the matrix. — The fossil is embedded in a 

 weathered block of greenish-gray limestone having a slightly 

 talcose feel, and soft enough to be easily scraped with a knife. 

 The matrix was examined both macroscopically and in thin 

 sections* for traces of other organic remains ; but beyond a 



* A thin section and fragments of the surrounding rock were submitted 

 recently to Dr. Charles Palache, who was kind enough to furnish the following 

 note upon their mineralogical characters : 



"The rock is a very soft greenish-gray limestone, somewhat greasy to the 

 touch. On the under surface it shows a concentric structure, the nodules being 

 small and developed about many centers ; but this structure is not sufficiently 

 pronounced to enable one to decide from it either for or against a concretionary 

 origin for the specimen. The rock dissolved readily in cold dilute acid, leaving a 

 residue which amounted to less than one-fourth of the whole, and proved on 

 examination under the microscope to be composed of fragments of feldspar and 

 scales of a kaolin-like mineral. It is doubtless to these scales, of kaolin that the 

 rock owes its greasy feel, for the proved absence of magnesia shows that talc is 

 not present, as was at first suspected. Silica is also absent." 



Am. Jour. Sci.— Fourth Series, Vol. IV, No. 20.— August, 1897. 



