22 University of Texas Bulletin 



erina in both states, Ornphalotrochus? sp. and a variety of Euomphalus 

 pernodosus M. and W. 



"The associated fauna is such as to force the conclusion that the up- 

 per Gaptank formation reaches as high as the base of the Lower Per- 

 mian (Permo-Carboniferous) if it does not sHghtly penetrate it. The 

 evidence of the faunas of the overlying formation is perfectly consis- 

 tent with this conclusion. 



"While a large percentage of the species of fossils found in the Gap- 

 tank formation is identical with or related to species from the Pennsy 

 vanian of the Mississippi Valley, yet many have very close relation- 

 ships with forms described from the Pennsylvanian and even Permo- 

 Carboniferous of Eurasia, especially the southern part of the con- 

 tinent. 



"Among the species with southern Asiatic affinities may be men- 

 tioned Spirifer cf. musakheylensis Dav., Productus group of P. gigan- 

 teus Waagen, Enteletes hemiplicatus Hall? aff. (Syntrialasma) hemi- 

 plicaiiis of Keyserling from Lo Ping, and Productus guadalupensis 

 comancheanus Girty, group of P. humholdti; three of those with north- 

 ern Eurasian affinities are "Pleurotomaria" group of P. altaica de 

 Vern., Uncimdus aff. wangenheimi Tschernyschew, and Euphemus 

 nodocarinatus (New Harmony variety) White, with E. carbonarius 

 Stuckehberg (Kart. Geol. Russ. 127) ; of species related to the Permo- 

 Carboniferous of the Alps and Sicily we have Enteletes aff. waageni 

 Gemm., Geyerella aff. Geyerellae of Schellwien from the Trogkofel- 

 schichten. 



"Even from this brief review it is evident that during the Pennsyl- 

 vanian time at least an intermittent connection was maintained be- 

 tween the waters of this part of west Texas and the Mississippi Valley 

 sea, as well as with the southern Eurasian region during the later 

 Pennsylvanian. 



"The fauna of the formations above the Gaptank — Wolfcamp to Gil- 

 liam — show little if any evidence of a connection with the Mississippi 

 Valley region after the close of the Gaptank. While these higher for- 

 mations contain some species common to the Mississippi Valley region 

 or related to them, yet they may all be accounted for as survivors of 

 the earliest migrcition." 



