WHITE.J CRETACEOUS FOSSILS OF COALVILLE, UTAH. 239 



54. Admctopsis suhfmiformis Meek. 



This form is ligurcd in anotlier part of this volume from a drawing by 

 Mr. Meclc. I have some doubts as to its generic relation with Nos. 52 

 and 53. 



bi). Baculites ovatus Say ? 



The only example of any Cephalopod that has been discovered in the 

 whole Cretaceous series at Coalville is a fragment of a small Baculites 

 tliat seems to belong to B. ovatus Say. It was found in thin-bedded 

 sandstone immediately overlying the strata from wlii(;h Mr. Meek ob- 

 tained the estuary forms that are mentioned under No. 29. 



The series of strata exposed at and in the neighborhoodof Coalville, as 

 represented by its invertebrate fauna, is a remarkable one in several re- 

 spects. There can be no doubt of the Cretaceous age of that whole series, 

 of strata, together with its fauna, as shown in the foregoing list of fossils ; 

 but yet, out of the lifty-five species there enumerated, only se\en, namely, 

 Xos. 5, 10, 11, 12, 40, 41, and o~), indicate the Cretaceous age of the stratti, 

 or that ihey belong to an earlier period than the Tertiary. Out of these 

 tifty-live species also only four of them, namely, Nos. 3, 10, 19, and 55, 

 have been found outside of the region adjacent to the east flank of the 

 Wasatch Mountains and extending southward to Northern Arizona, and 

 the identity of Nos. 3 and 54 is somewhat doubtful. Furthermore, about 

 half of these species have hitherto been found only at and in the imme- 

 diate neighborhood of Coalville, although they perhaps exist in the equiv- 

 alent strata of the region that lias just been referred to. 



The absence from this series of Cretaceous strata at Coalville of such 

 species as characterize the respective Cretaceous groups which have been 

 established makes it impracticable to refer them to any one or more of 

 those groups with certainty. Moreover, although the aggregate thick- 

 ness of the sti^ata there is greater than we should expect to tind any one of 

 those groups to possess the series seems to be a perfectly unbroken one, 

 both stratigraphically and paleontologically. I think thei'e is no leason 

 for doubt that the greater part of the series at least is referable to the Fox 

 Hills Group as it is developed and understood in Colorado and adjacent 

 parts of Utah and Wyoming. The possibility that the lower portion of 

 the series may be referable to the upper portion of the Colorado Groui^ is 

 suggested only by the greater thickness of the series than the Fox Hills 

 Group usually attains, and the presence in those lowest strata of the 

 Coalville section of Inoceramus prohlematicus. On the other hand this 

 species has been found at Old Bear River City associated with forms that 

 occm^ in the top of the second ridge at Coalville, the strata of which evi- 

 dently belong to the Fox Hills Group. The real relations of these Coal- 

 ville strata and their equivalents will doubtless be ascertained by tiacing 

 and studying the Cretaceous strata northwardly to the Missouri and 

 Yellowstone Rivers. 



These Coalville deposits were probably raado in comparatively shal- 

 low waters; yet the lithological evidence of it is no greater than that 

 presented by those widespread Cretaceous strata which contain the more 

 common and well-known marine forms. At least, the character of their 

 invertebrate fauna seems to have been greatly modified by the prox- 

 imity of a then existing western shore to the Cretaceous sea. This view 

 is supported by the presence of palustral, littoral, and estuary forms in 

 some of the strata of the series, but the modification referred to, while 

 doubtless due remotely to the same cause, is separate from such local 

 conditions as gave those estuary moUusks their congenial habitats with- 



