138 INVEETEBRATE FAZTNA OF DAKOTA FORMATION— WHITE, vol.xvii. 



the moutli of the Big Sioux River was deposited in saline waters, but 

 there is no reason for questioning the marine origin of the collections 

 made by Prof. Mndge in Saline County, Kans, T have no reason to 

 doubt that the Kansas deposit holds the same stratigrapliical position 

 in the Cretaceous series as does the Dakota formation, nor do I know 

 of any reason to doubt that it merges horizontally into the Dakota. 

 Still, I am disposed to exclude those Kansas deposits and their south- 

 ern and southeastern marine equivalents, when discussing the fauna 

 of the Dakota formation proper. Indeed, I think it is to be expected 

 that should any invertebrate remains be found in any of the Dakota 

 strata which are known to prevail in the great region westward and 

 northwestward from eastern Kansas and Nebraska, they will be such 

 as indicate a fresh- water habitat. 



EXPLANATION OF PLATE VIII. 

 Unto harhouri, p. 133. 



Fig. L Side view of an artificial cast from a natural inoliL 

 Fig'. 2. Dorsal view of the same specimen. 



Fig. 3. Side view of an artificial mold of a natural cast of a right valve of another 

 specimen of the same species. 



Unio (dovhifid specie-'^), ]). 133. 



Fig. 4. Side view of a natural cast of the interior of the shell. 

 Fig. .^. Dorsal view of the same specimen. 



Corhula hicksii, ]). 134. 



Fig. 6. Side view of the left valve; an artificial cast from a natural mold. 



Fig. 7. Dorsal view of the same specimen. 



Fig. 8. Front view of another specimen; also an artificial cast of a natural mold. 



Goniohasis jeffersonensis, p. 134. 



Fig. 9. Side view of an artificial cast of a natural mold. 



(loniohaHiR (douhtfiil species), p. 13,~). 



Fig 10. Side view of an .artificial cast of a natural mold. 



rirlparKS hiclsii, ]^. 135. 



Fig. n. Side view of an artificial cast of a natural mold. 

 Fig. 12. Side view of another similar cast. 



Pijrf/uJifera meekii, p. 13.5. " 



Fig. 13. Side view of an artificial cast of a natural mold. 



All the figures on this plate are of natural size except fig. 9, which is slightly 

 enlarged. 



