v/HiTE.vES.] DEVONIAN FOSSILS, MACKENZIE RIVER BASIN. 237 



Surface smooth or with obscure radiating strise. 



Shell substance punctate. (?) 



Dedicated to John S. Newberry, M.D., LL.D., Professor of Geology 

 and Paleontology in the School of Mines, Columbia College, New Yoi'k, 

 and lately State Geologist of Ohio, as a mark of appreciation of his 

 high scientific attainments, and in remembi-ance of a fi-iendship which 

 has continued uninterrupted during fifty years. 



Type: Bensselaria Johanni, Hall. 



Observations. — Several species of Eenssel.eria have an essentially 

 similar form, but thej- are alwaj's marked by strong I'adiating striaj, 

 which, as far as observed, are obscure, or visible in specimens of Neav- 

 BERRiA only in partial exfoliation of the surface, very much as they 

 appear in Amphigenia. On the interior of the pedicle valve Eens- 

 SEL-ERiA preserves two broad, strong, dental plates which reach nearly 

 to the bottom of the rostral and post-umbonal cavity, leaving a narrow 

 space for the muscular area, cjuite unlike that of the corresponding 

 valve of Newberria. It is from this narrow cavity, produced by the 

 encroachment of these strong dental plates, that we have the narrow 

 elongate rostral casts of Eenssel.eria, which are very dissimilar to 

 those of Newberria. 



In the brachial valve the thickened strong hinge jjlate of Eens- 

 SEL^iiRiA which supports the crura, does not exist in siiecies of New- 

 berria, and in the latter genus we have no knowledge, thus far, of the 

 existence of any interior loop or plate, as in Eenssel^dria. The ex- 

 ternal form and surface characters of Newberria are very similar to 

 those of Amphigenia, but the interioi' of the latter shell carries a 

 spoudylium or spoon-shaped process, an organ not present in New- 

 berria nor in Eenssel.eria. 



Sjaecies of Newberria are known to occur in the Devonian rocks 

 near Davenport, Iowa; in Manitou county, Missouri; and on the Mac- 

 Jienzie Eiver." 



(Professor James Hall, communicated in a letter dated February 5, 

 1891.) 



Newberria l.evis, Meek. (Sp.) 

 Plate 30, figs. 3, 4 and 4a. 



Rcnmehtria Irris, Meek. 1868. Trans. Chicago Ac. Sc, vol. I, p. 108, pi. xiii, 



fig. .s, and pi. xiv, fig. 4. 

 Not Rensselcria licvis, Hall. 18.59. Pal. St. N. Y., vol. Ill, p. 256, pi. xl, figs. 



2 a-b. 



Mackenzie Eiver, at the "Eamparts," and ten miles below the Earn- 



