APPENDIX E. — PALEONTOLOGY. 411 



Productus COSTATUS? 

 Plate III. Fig. 2. 



Reference, De Koninck, Recherches sur les Animaux Fossils, premiere partie, 

 page 92, pi. VIIL, fig. 3. 



The specimen figured is 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 same species. 



Productus semieeticulatus. 



Plate III. Fig. 3, 5 a and 5 b. 

 Reference, De Koninck, Recherches sur les Animaux Fossils, premiere partie, 

 page 83, pi. VIII., IX., and X. 



I refer, 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 flexuous, sometimes 

 preserving the bases of numerous spines, and at other times 

 entirely free from these appendages. Other specimens are pro- 

 portionally shorter and broader, and present the usual form of this 

 species, though none of them are larger than those figured. 



The specimens are all in limestone of a dark gray or brownish- 

 gray colour, from near Fort Laramie. Some impressions of the 

 same or a similar species occur in limestone from Flat-rock Point, 

 and other places in the neighbourhood of the Great Salt Lake. 



Productus (sp. indet.) 



Plate IIL Fig. 4. 



This species bears considerable resemblance to P. costatus, in 

 the aspect and marking of its surface, but its form is quite different. 

 It occurs on the Missouri River, near Weston, associated with 

 Ferebratulse and other species of Productus, Spirifer, &c. 



A species of Productus resembling P. punctatus in the character 

 of its surface, occurs on the Big Blue River, in soft shaly limestone ; 

 but the specimens are too imperfect for determination. The 

 occurrence of this and other species, shows the existence of car- 

 boniferous strata at several points after leaving the Missouri River, 

 and, in some instances, after crossing tracts of country that are 

 probably of cretaceous beds. 



