Mesozoic and Ccenozoic Geology and Paloiontology. 21 



Dr. Jumes Schiel* found the Cretaceous rocks west of Fort Atkin- 

 son, and described Inoceramus x>seudo-mytiloides. W. P. Blake, 

 from the fossils collected by Oapt. John Pope, identified these rocks 

 on the banks of the Red river, near Preston; Big Springs of the Col- 

 orado; Elm Fork of the Trinit}^ river; and a point 20 miles east of the 

 Sand Hills, on the Llano Estacado. 



In 1856, William P. Blakef announced generally the Cretaceous 

 age of the extensive table lands on the 35th Parallel from the 101st 

 to the 110th Meridian, known as the Llano Estacado. Thous^h Wis- 

 lizenus as earl}^ as 1848 had described it in the bluff's of Gallinas 

 Creek, and Dr. Schiel, Dr. Randalf and Lieutenant Simpson as well 

 as Jules Marcou had testified to its existence in various places in the 

 exposed bluff's found upon these plains. The strata are nearly hori- 

 zontal, and principal!}^ white or grey and highly calcareous, but some- 

 times intercalated with gre}^ or blue marl or clay. Prof. James HaU 

 described, from False Washita and other localities in the westi 

 Gryphoia loitcheri^ var. navia. 



Meek & Hay den]; described, from near Fort Union, Nebraska (later 

 called Fort Union Group), Cyclas formosa^ now Splicer ium for mo sum ^ 

 C, sif.beUipticus, now S. suhelUpticum, Bulimus teres^ now Columna 

 teres, B. vermiculus, now C. vermicida, Pupa helicoicles, Limnea ten- 

 uicosta, which is made the tjpe of the genus Pleurolimnea, Physa 

 longiuscula, now Bulimus longiusculus, P. rhomboidea, now B. rhom- 

 hoideus, P. nebrascensis, Velletia minida, now Acroloxus minutus, 

 Paludina leai, now Viviparus leai, P. i^etusa, now V. retusus, P. 

 leidyi, now V. leidyi, P. trochiformis, now V. trochiformis, Valvata 

 parvula, Jlelania minutula, now Jlicropyrgus minutulus, 31. multis- 

 triata, now Campeloma multistriatum, 31. nebrascensis, now Goniobasis 

 nebrascensis; from Moreau river, Cyrena moreauensis, now Gorbicula 

 moreauensis, Gyrena intermedia, now Gorbicula nebrascensis; from the 

 Bad Lands of the Judith river, Gyrena occidentalis, now Gorbicula 

 occidentalism Gorbula subtrigonalis, G. perundata, G. mactriforinis ^ 

 Unio priscus, Physa subelongata. now -Bulimus subelongatus, Planor- 

 bis subumbilicatus, Paludina vetula, now Gampeloma vetulum, P. con- 

 7'adi., now Viviparus conradi, 3Ielania convexa, now Goniobasis con- 

 vexa; from Fort Clark, Bulimus limnwformis, now Thaumastus limnm- 

 formis, Paludina multilineata, now Gampeloma multilineatum, P. 

 peculiar is, now Viviparus j^eculiar is; from Little Horn river, Planor- 



* Expl. & Sur. R. R. Miss. River to Pacific Ocean, vol. 2. 



t Pacific R. R. Sur. vol, 3. 



t Proc. Acad. Nat. Sci,, vol. 8. 



