38 Hill Paleontology of the Trinity Division. 



nearest ivalcotti occurs in the very top of the Jura of Central 

 Volga stage, supposed by some to be similar to the Purbeck in the 

 upturn at Malm. The obscuration of a portion of the sutures 

 occurs over the most important part of the outer side, and the 

 structure of the abdomen, which is rounded and has no keel, 

 is not very consistent with the reference either to the Neumayria 

 of the Jura or the so-called Neumayr'ta of the Cretaceous. Never- 

 theless it agrees better with those of the Jura than the Cretaceous 

 ones referred to the same genus by Nikitin." 



AVhatever may be the range of this genus in Europe, the writer 

 is inclined to the belief, from the stratigraphy and association, 

 that its occurrence in Arkansas is lowest Cretaceous, and Pro- 

 fessor Hyatt's opinion serves to strengthen the position of the 

 writer in his reticence in earlier papers in expressing a more 

 definite assignment of the Trinity beds before minutely studying 

 the accompanying faunas. The specimen was collected in the 

 banks of Town creek, one mile southeast of Murfreesboro, Ar- 

 kansas. Named in honor of Mr. C. D. Walcott. 



Acanthoceras (?) jusCmee sp. nov. 

 Plate VII, Figs. 1, 2, and 3. 



Discoidal thin and flattened in general outline, deeply um- 

 bilicate, marked by numerous simple, gently sinuous ribs extend- 

 ing across the convolution and separated by shorter ribs, which 

 disappear near the middle of the convolution ; abdomen oblately 

 rounded ; suture lines not preserved in specimens found ; um- 

 bilicus (fig. 2) narrow, depressed. 



This species occurs in a coarse sand in the Trinity beds of 

 Travis Peak post-office, in western Travis county, Texas, only 

 four specimens having thus far been found. It is preserved as a 

 cast, unpropitious for the preservation of the shell structure. It 

 is the only ammonitic form thus far found in the Trinity Divis- 

 ion, excepting Neumayria walcotti, but is of little value in deter- 

 mining the stratigraphic position of these beds. 



Professor Hyatt has provisionally referred it to the family 

 Aq&nthoceratidx, and suggests a resemblance to A. rem-ondii Gabb, 

 from the Cretaceous of California. Our species, however, in the 

 writer's opinion, is quite different in general aspect, being very 

 much more flattened, more rectangular at the tlorsum, and pos- 

 sessing wider convolutions. It has some external resemblance 

 also to the genus Hoplitcs. 



