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Art. II. — Notice of the genus Chonetes, as found in the Western States and Territories 

 with descriptions of eleven new species. By Joseph G. Norwood and Henry Pratten, 

 of the Illinois Geological Survey. 



This genus was established by Fischer in 1837, to separate from the genus Leptaina 

 such shells, having the same general form with those of Dalman's genus, as possess 

 a row of spines on the margin of the dorsal valve along the cardinal area. At that 

 time there were six species known. Up to the year 1843, other species were added 

 by European Geologists ; and, in that year, our most distinguished paleontologist, 

 Professor Hall, described two from this country, G. cornuta and G. setigera, which he 

 united to the genus Strophomena of Rafinesque. In 1847 M. de Koninck published 

 his excellent Monograph on the genus, in which he not only enumerated, but described 

 every known species, amounting, in all, to twenty-three, including all those known in 

 this country. Since then, in 1852, Dr. D. D. Owen described a new species from 

 Missouri, making all the known published species, up to the present time, amount to 

 twenty-four. The two species already mentioned as described by Prof. Hall, belong 

 to New York ; the third one, described by M. de Koninck, the G. Shumardiana, is 

 from Kentucky, and named by him in honor of the zealous geologist and palaeontologist 

 who discovered it. 



We now make known eleven new species from our Western States and Territories, 

 and announce the discovery of two others of the known species of Europe in our western 

 formations, viz: G armata, of M. Bouchard, and G. Sarcinidata, of Schlotheim. 



Six of these species were found at a single locality, the " Devil's Backbone," in 

 Illinois, in limestone belonging to the Devonian period ; one, two miles west of Jones- 

 boro, Illinois, in limestone of the same age; two, in the Mountain limestone of 

 Burlington, Iowa ; four are from the coal measures ; and one, the Flemingii, is from a 

 formation, the age of which has not yet been determined, but which, probably, belongs 

 to the Coal period. It was found by Mr. Pratten ten miles northwest of Richmond, 

 Missouri. 



The whole number of species known to M. de Koninck, in 1847, 23 



Added by Dr. D. D. Owen, (U. S. Geological Survey,) . . 1 



Addition made now, . . . . . . . . 11 



Making the present number known, . . . . . 35 

 Seventeen of these species occur in the Western States of Northern America. To 

 these add the two species found in New York, and we have nineteen species found in 



