38 Hill — Palcontologij of tlic TnnUij TJiviHLu)i. 



nearest walcutti occurs in the very to}) of the Jura of Central 

 Volga stage, supposed Ijy some to be similar to the Purljcck in the 

 ui)turn at JNIalm. The obscuration of a portion of the sutures 

 occurs over the most important ])art of the outer side, and the 

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

 is not very consistent with the reference either to the Neunwyria 

 of the Jura or the so-called Neuinayr'w of tlie Cretaceous. Never- 

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

 ones referred to the same genus l)y Nikitin.'' 



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

 is inclined to the belief, from tlie stratigra])hy and associaticm, 

 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 minutel}'^ 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. AV'alcott. 



Acanthoceras (?) jus inae sp. nov. 



Plate VII, Figs. 1, 2, and 3. » 



Discoidal thin and flattened in general outline, deeply um- 

 l)ilicate, marked l)y numerous simple, gently sinuous riljs extend- 

 ing across the convolution and sei)arated l)v shorter ril)s, which 

 disappear near the middle of the convolution ; abdomen o))late]y 

 rounded ; suture lines not ])reserved in specimens found ; um- 

 bilicus (flg. 2) narroAV, depressed. 



This species occurs in a coarse sand in the Trinity Ijeds 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 l;xr found in the Trinity Divis- 

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

 mining the stratigraphic ]:>osition of tliese beds. 



Professor Hyatt has }>rovisionally referred it to the family 

 AcanthoccratidiK, and suggests a resemblance to A. remoii(lil (.!abb, 

 from the Cretaceous of Califoruia. Our species, however, in tlu' 

 writer's o})inion, is ([uite diiferent in general asi)ect, l)eing very 

 much more flattenetl, more rectangular at tlie dorsum, and i)OS- 

 sessing wider convolutions. It has some external resemblance 

 also to the genus HopUtes. 



