on the Fossils of the older Deposits in the Rhenish Provinces. 329 



more considerable extent than the eighty-five Devonian. The mountain Hmestone 

 of Yorkshire contains the greatest number. Some have been discovered in the upper 

 group of the Carboniferous system in the Ural mountains*. The species most widely 

 distributed are the G. Henslowi, Sow., obtained in the Isle of Man, from the culm- 

 measures of Devonshire, in Staffordshire, and at Ecton in the state of New Yorkf ; 

 the G. Listeri, Mart., from Derbyshire and the province of Liege, stated also to 

 occur in India on the banks of the Ganges \ ; the G. carbonarius of Goldfuss from 

 Yorkshire and the banks of the Rhine; the G. spheericus, Mart., from Derbyshire, 

 the Isle of Man, Yorkshire, the province of Li^ge, Herborn, and the state of New 

 York ; and lastly, the G. striatus, Sow., is met with in nearly all these locahties. 



The Goniatites have been but seldom noticed in the ancient beds of North Ame- 

 rica ; and those which have been mentioned are from the Carboniferous system. 

 According to Conrad there are none in the Trenton group which form the lower 

 part of the Silurian system, and they are extremely rare in the upper beds of the 

 series. The genera Trocholites and Phragmolites of the state of New York seem to 

 approach in structure the Goniatites^. 



From the sagacious observations of M. von Buch, naturalists are well acquainted 

 with the characters in which the Goniatites or Ammonites of the ancient beds differ 

 from the true Ammonites of the secondary beds ; but if the Goniatites themselves be 

 attentively examined, characters will be observed in the exterior contour of their 

 chambers indicative of the antiquity of the system in which they are found. Thus 

 the G. Noeggerathii, de Buch, and G. subnautilinus, id., from the Silurian schists of 

 Wissenbach, belong to the first section, which is characterized by rounded or very 

 slightly inflected lobes. Of all the families of the Ammonites, these have the edges of 

 the chambers the most simple. In the Devonian system the lobes are more decided, 

 angular and linguiform, but the dorsal lobe is constantly simple. In the Carboniferous 

 system, on the contrary, nearly all the species (four or five only excepted) have the 

 dorsal lobe divided. From these to the Serratites of the muschelkalk, and thence 

 to the true Ammonites of the lias and the later formations, the passage is perfectly 

 gradual in relation to the chambers ; but this progression does not appear to exist 

 relatively to the dimensions of the shells, the Goniatites being almost always small. 



In general the Cephalopods appear to have been much more extensively distri- 

 buted in the ancient European than in the American seas. As to the number of 

 species in the three systems, it will appear to be much more considerable in the 

 Devonian system than in the two others. 



* See the forthcoming work on Russia alluded to ante, p. 306. 



t State Reports, New York, 1838, p. 110; 1839, p. 62. 



t De Buch. 



§ State Reports, New York, 1838, p. 118-119; 1839, p. 63 ; 1840, p. 371. 



