68 



University of Texas Bulletin 



Helicocryptus mexicanus 



Bose 



Holectypus limitis Bose 

 Enallaster bravoensis Bosc 

 Epiaster aguilerae Bose 

 Hemiaster calvini Clark 



H. radiatus Sowerby 



H. cenomanensis Gueranger 

 E. lepidus de Loriol 

 E. triangularis d'Orbigny 

 H. latigrunda Peron and 

 Gauthier 



DESCRIPTION OF SPECIES' 

 CEPHALOPODA 



NAUTILUS TEXANUS Shumard 



i860: Nautilus texanus Shumard, Trans. Acad. Sci., St. Louis, 1, 1856-60. 



1889: Nautilus texanus Hill, Geol. Surv. Texas, Bull. 4, p. 21. 



1893: Nautilus texanus Cragin, Geol. Surv. Texas, 4th Ann. Kept., p. 236. 



1895: Nautilus washitanus Cragin, Colo. Coll. Stud., 5, p. 67. 



1902: Nautilus texanus Shattuck, U. S. G. S., Bull. 205, p. 34, pi. XXIII, figs. 1-2, 



pi. XXIV, figs. 1-2. 

 1920: Nautilus texanus Adkins and Winton, Univ. Texas Bull. 1945, p. 32, pi. 20, 



figs. 1-2. 

 1920: Nautilus texanus Winton and Adkins, Univ. Texas Bull. 1931, pp. 58, 61, 66. 



This is the commonest Cdmanchean Nautilus, and has a known range 

 from the basal Duck Creek limestone (at Denison, Texas) to the Buda 

 limestone (at Austin, Texas). It has a zone of abundance in the top of 

 the Weno limestone, and one in the top of the Fort Worth limestone. 



NAUTILUS sp. 



The upper Pawpaw clay contains considerable numbers of small Nautili 

 of a size about one-third that of Nautilus texanus Shumard. These Nau- 

 tili are more closely coiled, have a smaller umbilicus, a much thicker and 

 lower volution, and apparently are smooth. The species is not described 

 here because of the poor preservation of the material at hand. 



1 Types and figured material are deposited in the Bureau of Economic Geology, 

 Austin, unless otherwise specified in the text. The types at Austin are in a metal 

 locker in the fireproof vault of the University of Texas Library. Most of the photo- 

 graphs were made by Mr. F. Christiansen, Austin, but for some I am indebted to 

 Professor John Davis, Fort Worth. 



