Description of the Fossils in the older Deposits of the Rhenish Provinces. 343 



tubercles, setting oflP from the inner edge and becoming smaller as they approach two-thirds of the 



side where they disappear entirely. The whole surface of the shell is moreover covered with fine 



radiating strias which become weaker as they approach the aperture. 



This species is distinguished from the preceding, to which it is nearly related by the form of its back, 



which has a tendency to become sharp instead of being rounded, and by its much more elongated tubercles. 



From the iron mines of Brilon ; very rare. 



21. Goniatites tenuistriatus, nob. Tab. nost., XXVI. f. 7,7 a, 7 b, and 8, 8 a. 



Shell discoid, subumbilicated, very depressed, composed of seven to eight volutions, of which the last, 

 which is very large, constitutes alone almost the whole of the shell : it appears proportionally more 

 enveloping than the first. Umbilicus very open, cuppel-shaped. Suture simple as far as to the 

 last volution, where it is bordered by a slender lamellar fold surmounted by a wider and more 

 rounded one. Back narrow and smooth at the anterior part where it is without septa. Toward the 

 posterior fourth of the last volution the flat part of the back sinks downward slightly so as presently 

 to form a true channel or groove with a flat bottom of a millimetre in width, neatly bounded by 

 two little bands ; this groove then continues to the apex of the spire. The surface of the volu- 

 tions, except the last, is divided into two parts ; that which comprises the inner edge to the suture 

 has simple striae, which, setting off" from the latter, rise straight up to a line which bounds this first 

 third. Against this lateral line commence finer and more close-set striae which take a direction 

 obliquely upwards, and soon become subdivided into three or four much more delicate and regularly 

 undulated striae, having the appearance of a watered stuff. These striae then pass across the back 

 horizontally. The lateral line which separates the two systems of striae appears to be lost upon 

 the last volution, as well as the second system of striae, which becomes weaker and disappears at 

 the same time as the dorsal groove. The second half of the last volution then only offers simple 

 striae which extend from the suture to the back. 



The specimens which we have represented were not circular, but elongated like an Ellipsolite, still 

 without presenting any appearance of malformation. A younger individual, which has been figured, and 

 is magnified (fig. 8, 8 a) to show the first volutions, is perfectly regular in its form. 



From the ferruginous limestone of Oberscheld ; rare. 



22. Goniatites 



In the iron mines of Wetzlar is found a species of Goniatite which appears to be related to G. retrorsus, 

 but the specimens we possess are too much deformed to enable us to decide. They are all elliptical and 

 more or less depressed ; the wide and rounded back is bordered by two distinct channels ; and upon the 

 sides may be observed traces of striae, which, without being altogether parallel to the edges or longitu- 

 dinal, as in G. striatus, Sow., are nevertheless very long, and form with the lateral channel an extremely 

 sharp curvilinear angle. 



Wetzlar on the Lahn ; common. 



Aptychus vetusttis, nob. Tab. nost., XXVI. f. 9. 



We refer to this genus a blackish impression left upon a fragment of the Eifel limestone and which is 

 composed of two thin symmetrical subtriangular plates only presenting indistinct, undulated lines of 

 growth with unequal spaces. 



Eifel ; very rare. 



Although we have placed this fossil here, we do it without any pretension to determine its zoological 

 classification. 



2y2 



