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Show APUKDIX E.- PALEONTOLOGY. 411 PRODUCTO^ COSTATtJS? P* ATO IH. Fw. 2. Reference, De Koxdnok, Btfche/ ofres sor lea Animaux Fossils, premiere partre,' ^ page 02, pi. V l l t , fig. 8. . The specimen figured isr apparently a young individual of this species, in a bad state . of preservation. The species is also cited by De K., from the Missouri River, from whence the specimen figured was obtained* Some other fragments from the Platte River appear . to belong to the pame species* • • • t PRODCTCTUS SEB* IR* TiCtTLATOS. PLATI, IJL FIO. 8, 6 a and 5 b . . Referenoe, De Kbninok, Recberahes snr Jee Amman* Fossils, premiere partie, page 68, pi. VIII., IX., and X. ^ 1 refei1, with some hesitation, the specimens here figured, to this very variable species. One or two of the specimens are very . narrow and much elongated; the striae are flexuoufc, sometimes preserving tliq bases of numerous spines, and' at other times, entirely free, from these appendages. Other specimens lire proportionally shprter and broader, and present the usual Form of this species, though none of them are larger than* those figured. The- specimen*, are aH in limestone of a dark gray or brownish-gray - colour, from near Fort Laramie. . Some impressions of the samp or a'similar species occur in limestone from Flat- rock Point, and other places in the neighbourhood of the Great Salt Lake. * f PROITCCTUS :-( sp. indet.). PLATS III: Fio. 4. This species bq& r* considerable, resemblance to P. costatus, in the aspect and marking of its^ surface^ but its forpids quite different. . It occurs, on the Missouri River, near Weston, associated with Ferebratulae and other species of Produettu, Spirifer, & o. V' A. species of Productu* resembjing P. punctatus in the character, of its fQrface, occurs on the BigBlue River, in soft shaly limestdne; but thew specimens aire, toe imperfect for . determination. The occurrence of { his and other species, shows, " the existence of carboniferous Strata at several points after leaving tBe Missouri River, and, in some instances, after crossing tracts of country that are probably of cretaceous beds. ., • .• \ |