348 C. D. WALCOTT — THE TERM "HUDSON BIVEB GROUP." 



3on is fairly well established; that it is present in the Mississippi valley or 

 the interior of the continent is well known. The barrier that prevented the 

 fauna of the interior sea from extending into the valley of the Hudson 

 during the Later part of the Hudson period appeals to have been a shallow- 

 in lt <>f tin- sea through central New York about the time of the deposition of 

 the passage beds between the Utica shale and the Lorraine shales, as shown 

 in the Lorraine section. To the west and north of Rome, the Hudson ter- 

 rane increases in thickness; and at Lorraine, in Jefferson county, I measured 

 the following section the past summer: 



Section along the south branch of Sandy creek, Jefferson county, N. Y. 



Feet. 



1. Trenton limestone as exposed in the town of Ellisburgh__ !'■"> 



2. Dark bituminous shale in bands, alternating with a smoother lead-colored 



shale. Thin layers of a gray, fine-grained, calcareous sandstone occur at 

 various horizons in the shale. This shale is characterized by the fauna of 

 the Utica shale* 180 



Fossils: Endoceras proteiforme, Triarthrus beckii, and Trinucleus 

 concentricus. At 150 feet up in the shales a few minutes' work of collect- 

 ing gave: Leptcena sericea, Orthis testudinaria, Cleidophorus planulatus, 

 Tellinomya, sp. und., Triarthrus beckii, and Trinucleus concentricus.* 



3. Alternating bands of shale and gray, fine-grained, calcareous sandstone ; the 



shale predominating 100 



Fossils: Diplograptus pristi», ERppothoa inflata, Palesthara (sp. 

 undet.), Monticulipora (2 sp. undet.), Pholidops cincinnatiensis, Tre- 

 matis terminalis, Leptcena sericea, Slrophomena alternate, Orthis tes- 

 tudinaria, Zygospir'i mud.^in, Avicula insucta, Modin/op.si.i <t,f<l<,ntoides, 

 Cleiodophorus planulatus, Xucula levata, Bellerophon eancellatus, Pleu- 

 rotomaria (small sp. undet.), Endoceras prof' iforme, Triarthrus hen' 

 Calymene eallicephala. At the summit of this belt I found : "Pholidops 

 subtruncata, Leptcena seriea, Orthis testudinaria, Cleidophorus planula- 

 tus, Ambonychia radiata, ami Triarthrus heckii. f 



I. Gray, line-grained, calcareous sandstone, with partings of black and drab 

 -ha]'-.: yielding on Sandy creek the folio wing fauna: Leptcena se Stro- 



phomena alternata, Ambonychia radiata, Modiolopsis modiolaris, Cleido- 

 phorus planulatus, and Calymene eallicephala. On tin; Salmon river, at 

 Pulaski, Oswego county, the base of tin- series i- Been ami about fifty I 

 of strata. Fossils are abundant, but as they are better preserved in the 

 drift to th<- south in Lewis ami Oneida counties, the following typical 

 species only were collected: Monticulipora diseoidea, M. gracilis, <'rt< i- 

 ana G yptoerinusdecadactylus, Leptama sericea, Strophomena alternata, 



Ambonychia radiata, Modiolopsis modiolaris, Nucula levata, Cleidophorus 

 planulatus, Cyrtolites ornatus, CornuUtes curvatus, ami Calymene ealli- 

 cephala. At Salmon river fall- the -uii i in it uf this series i- seen jusl above 



the line '•{ lie- Motion, Ihe fir* I folly f'-.-t "I lie' ibale i- < •< > 1 1 • ■< • :it < • « 1 by drift ilep'ixitx, lilll ell 



ttii' inch ••( Sandy creek may be seen in numeroux expoaun 



; 1 1,1- i- the big heal Bone lit which / und. 



the line ol Sandj Mouther of this series of rock exposed. 



