white.] LARAMIE FOSSILS FROM BEAR RIVER VALLEY. 243 



9. Corbula pyriformis Meek. 



This is also an abundant species in the lower beds, and, like many of 

 its associated bivalves, a large proportion of the examples have both 

 valves unseparated. It is figured and described in vol. iv, U. S. Geol. 

 Sur. 40th Parallel and also in U. S. Expl. Great Basin of Utah (Simp- 

 son). 



10. Corbula englenianni Meek. 



Probably only a variety of No. 9 (loc. tit.). 



11. Blnjtophorus priscus Meek. 



This is evidently a littoral pulmonate, closely related to Melampus, 

 and it doubtless had a similar saline habitat. It is the type of the genus, 

 and is described and figured by Meek in vol. iv, IT. S. Geol. Sur. 40th 

 Parallel, and also in IT. S. Expl. Great Basin of Utah (Simpson). 



12. Bkyiophorus meehii White. 



This is possibly only a variety of No. 11, but the observable differences 

 seem to be of specific value. It is described in Powell's Report on the 

 Geology of the Uinta Mountains, p. 118. 



13. Limncea nitidula Meek. 



Mr. Meek figured and described this species in vol. iv, U. S. Geol. 

 Sur. 40th Parallel. It is quite abundant in some of the layers near 

 Mellis Station, where it is associated with numerous fresh- and brackish- 

 water forms. 



14. Acella haldemam White. 



Among the siliceous debris remaining after an acid solution of some 

 pieces of calcareous shaly rock found among the fossiliferous layers near 

 Mellis Station, several examples of this species were discovered. It has 

 never been discovered elsewhere, and so far as I am aware no other 

 species of this genus has ever been founcl fossil. It is important as 

 adding another indication of the great degree of differentiation which the 

 pulmonate mollusca had attained at that early epoch. It is described in 

 Bull. U. S. Geol. Sur. Terr. vol. iv, p. 714. 



15. Planorbis f 



Among the debris associated with Nos. 14 and 15, numerous examples 

 of a minute Planorbis were found. They are all of nearly uniform size, 

 which suggests the possibility that they are adult $ but they are prob- 

 ably young examples of a larger species. No other examines of Planor- 

 bis were found in the lower beds, but in the upper ones at the Evanston 

 coal-mines some fragments of another but undetermined species were 

 found. 



1G. Bulinus longiusculus Meek & Hayden. 



Among a considerable number of examples found in the upper beds at 

 the Evanston coal-mines, referable to Bulinus, are some that I refer with 

 some confidence to B. longiusculus and B. subelongatus respectively. The 

 former was originally discovered in the Fort Union, and the latter in the 

 Judith Eiver beds, both in the Upper Missouri Eiver region ; and both 

 are figured and described in vol. ix U. S. Geol. Sur. Terr. 



17. Bulinus subelongatus Meek & Hayden. 



A single specimen found associated with Nos. 13, 14, 15, and others 

 in the lower beds near Mellis Station, appears to belong to this species. 

 See, also, remarks under No. 16. 



