430 



PROCEEDINGS OF THE ACADEMY OF 



Names of Genera. 

 Mosasaurus. 

 Saurocephalus. 

 Callianassa. 

 Pleurotoma. 

 Busyeon. 

 Pseudobuccinum. 

 Fasciolaria. 

 Cypraea. 

 Xylophaga. 

 Pulvenites. 

 Cassidulus. 



Position in Nebraska. Localities in the States. Position in Europe. 

 Ft.P.G.&FoxH.Bds. N. Jersey and Alab. Wh.Chk.&Maest.B. 



New Jersey. 

 Base Ft. Pierre Gr. " " 

 Ft.P.G.Up.pt.&FoxH.B. 

 Fox Hills Beds. 



White Chalk. 



u a 



Wh.Chk.&Maest.B. 



u 



Fox Hills Beds. 



Tennessee. 

 Alabama. 



Mississippi. 

 Alab. and Miss. 



Maestr. Beds. 

 White Chalk. 



Of this list of eleven genera, the following three, viz. Busycon, Pseudobucci- 

 num and Xylophaga, have not yet, we believe, been found iu the old world so 

 low as the Crotaceous ; while the genus Fasciolaria is there said to extend no 

 lower tLan the very latest member of the Cretaceous, (the Danien of D'Orbigny,) 

 above the Maestricht beds. The following seven of these genera, viz. Callia- 

 nassa, Busycon, Pleurotoma, Fasciolaria, Cyprcea, Xylophaga, and Cassidulus, pass 

 into the Tertiary, and are represented in our present seas; while the genus 

 Pseudobuccinum will probably be also found in the Tertiary, since we know at 

 least one species of it still living.* 



At the same time that we are already aware of the occurrence of eleven or 

 more genera, in our Upper Series of American Cretaceous rocks, not known to 

 have been found below the horizon of the Upper Chalk in Europe, we can re- 

 member only three that have been identified in this Upper Series, which are sup- 

 posed not to range above the Lower Chalk of the old world. These are Capri- 

 nella, Goniomya, and Macrabacia.f Of each of the latter two genera we cer- 

 tainly know one species in our Fox Hills beds; but the occurrence of the first 

 in our Upper Series is very doubtful, since it has only been identified from a 

 single imperfect specimen, that will probably be found to belong to some other 

 group. 



In addition to the general upward tendency, so to speak, of the genera in this 

 Upper Series, both in Nebraska and farther eastward, we would also remark 

 that a few of the forms found in our Fox Hills beds, particularly of the Gastero- 

 poda, present such close specific affinities to Tertiary shells, that we would have 

 doubted the propriety of referring them to the Cretaceous epoch, were it not 

 for the fact that we find them associated in the same bed with Baculites, Am- 

 monites, Scaphiles, and other Cretaceous genera and species. 



Although we have not been fully able to satisfy ourselves that any of the 

 species yet known from the Upper Cretaceous Series of Nebraska are certainly 

 identical with Upper Chalk forms in the old world, many of them are undoubt- 

 edly closely allied representatives, and we think the following will probably 

 prove to be common to this horizon in Nebraska and Europe, viz. Nautilus De- 

 kayi, Scaphiles Conradi, Baculites anceps, and Gryphcea vesicularis. At any rate 

 Nautilus Dekuyi is closely related to some foreign forms, and is supposed bv 

 D'Orbigny to occur in the Upper Chalk of Europe. Scaphiles Conradi, also, 

 seems scarcely distinguishable from an Upper Chalk form found in Germany, de- 

 scribed by Roemer under the name of S, pulcherrimus ; and we find in our Fox 

 Hills beds a Baculite we cannot distinguish from a Texas shell referred by Dr. 

 F. Roemer to B. anceps of Lamarck. We would remark, however, that if D'Or- 

 bigny's figures of Lamarck's species represent the sutures accurately, the Ame- 



* P. ampullaccum, (= Bullia ampulacea of Middendorff.) from the Great Schantar- 

 Tsland. 



t We are aware the genus Belemni/es is not known to extend up into the Upper Chalk 

 in Europe, and that Dr. Morton described a B. ambiguus from New Jersey. Dr. Leidy, 

 however, has decided that it is a spine of a Fish. 



[Dec, 



