44 COLORADO COLLEGE STUDIES. 



( See p. 277. ) In the '• Contribution to the Invertebrate Paleon- 

 tology of the Texas Cretaceous," published in the same report, 

 the present writer recorded a few fossils from beds referred 

 to, in doubtful terms or in quotation-marks, as of Vola equiva- 

 lency (/. c, p. 147, etc.). He there purposely implied doubt or 

 placed the word, '"Vola," in (juotation-marks, quoting from 

 the labels accompanying the specimens collected by Mr. TaflP's 

 field-party, feeling doubtful concerning the supposed dis- 

 covery of the Vola in that region and never having examined 

 the region personally. In the sunnner of 1898, however, after 

 the publication of his " Contribution," he visited Denison, in 

 the course of an extended expedition, and studied the matter 

 in the field, and so independently arrived at the same opinion 

 that has been announced by Hill in the Bulletin of ihc Geologi- 

 cal Society of America (Vol. V) viz., that no suflicient evi- 

 dence of the existence of an equivalent of the Vola limestone 

 in the Red river district has as yet been found. 



Paleontologically, the Grayson and the Shoal creek terranes 

 have little in common. In his "Mesozoic Echinodermata of 

 the United States" (Bui. 97 U. S. Geol. Surv.), Clark gives, 

 presumably on Hill's authority, the Shoal creek limestone as 

 the source of his Hemiaster calvini, the latter being appar- 

 ently synonymous with the Epiaster hemiaster iniis, nob., an 

 echinoid common in the Grayson marls in northern Texas. 

 It is possible that the Gryphcea mucronata of the Grayson 

 limestone beds of Travis county may extend up into the 

 basal part of the Shoal creek limestone; but to the best of the 

 writer's recollection, he has never observed such an occur- 

 rence.* 



The following list includes all of the fossils that the 

 writer has identified from the Grayson terrane, nearly all of 

 which have been collected by the writer in Grayson County: 



* In a letter received from State Geologist Dumble of Texas, since this was 

 written, and just as this MS. is going to press, speaking of the ' Vola,' he writes that 

 the Gri/phcea extends " uj) into tlio solid limestones to a liciglit of four or five feet." 

 But from his use of the word, "limestones" (in the plural), I am in doubt as to 

 whetlier he here refers to the lower part of tlio tnain stratum of the Shoal creek 

 limestone, or to tlie separate bod or beds of solid limestone underlying it. In either 

 case, it would seem to indicate only a transitional liorizou such as occurs at the 

 limits of most of the terranes of the Comanche series. 



