236 REPORT UNITED STATES GEOLOGICAL SURVEY. 



24. Tellium f modesta Meek. 

 See remarks under No. 22. 



25. Tellina (Areopagia) utahensis Meek. 

 See remarks under No. 22. 



26. Corbula nematopliora Meek. 



Meek reports the type specimens of this species from Southern Utah. 

 I figured an example from that region in vol. iv, U. S. Expl. and Sur. 

 West of the 100th Meridian, which is probably of this species. The 

 examples that I have referred to at Coalville were found associated with 

 true marine, and not brackish- water, forms ; as is also the following 

 species. A figure of Mr. Meek's type is also given in another part of 

 this volume. 



27. Corbula dubiosa White. 



Found also in the valleys of Bear Elver and Sulphur Creek. See notes 

 on Cretaceous fossils of Bear River Valley. 



28. Martesia 1 



Too imperfect for specific determination. 



29. Melampus antiquus Meek. 



In No. 16 of Mr. Meek's section, which he found exposed in Carleton's 

 coal-mine about two miles southwestward from Coalville, he discovered 

 a very interesting group of fossils, being Nos. 12, 17, 21, 29, 30, 32, 35, 

 36, 46, 47, and 49 of the foregoing list. Soon after his visit there the 

 mine was abandoned and the fallen debris has so obscured the strata that 

 no further collections from them have ever been made. Neither has any 

 discovery of this deposit ever been made in the neighborhood or else- 

 where, although one or two of the species have been doubtfully identi- 

 fied from Cretaceous strata elsewhere in Utah. Two of these eleven spe- 

 cies of mollusks, Nos. 29 and 30, are palustral or littoral pulmonates ; 

 two, Nos. 17 and 49, are fresh-water branchifers ; four, Nos. 21, 32, 35, 

 and 36 are brackish-water forms, and the remaining three species, Nos. 

 12, 46, and 47, may be regarded as marine forms. To the latter may be 

 added a Cardium, mentioned by Mr. Meek, but not enumerated in the 

 foregoing list; and to either the brackish or marine forms may be added 

 the Anomia, also mentioned by Mr. Meek as occurring with the others. 

 This last-named species may be identical with the one found by myself 

 in the sandstones of the second ridge and mentioned under the head of 

 No. 6 ; but it is probably not the same. 



This mixture of palustral, fresh- and brackish-water and marine mol- 

 lusks may be taken to indicate an estuary origin of the strata containing 

 them, although a somewhat similar admixture is found in a large part 

 of the Laramie Group, extending over an area so wide as to make it 

 certain that these deposits at least were made in a large, brackish- water 

 sea. However, the evidently limited extent of this Coalville deposit, and 

 the presence in it of so large a proportion of marine forms, may be re- 

 garded as almost certainly indicating its true estuary origin. This view 

 is also supported by the evidence that a western shoreline to the Cre- 

 taceous sea existed not far distant from this locality. The Physa, No. 31 

 of the list, was found among the marine forms of the sandstones of the 

 second ridge of Mr. Meek's section. This also indicates a then neighbor- 

 ing shore-line, but not necessarily an estuary ; but the presence of brack- 

 ish- and fresh- water branchiferous mollusks, as in No. 16 of that section, 

 seems to plainly indicate an estuary origin of the strata containing them. 

 These last-named mollusks, as well as their pulmonate associates, are 



