338 Viscount (I'Archiac and M. de Verneuil's 



sharp, as deep as it is wide, or double its width if the latter be measured at half its height. Dorsal 

 saddle rounded ; lateral lobe very large, slightly curved backward, without reaching the depth of the 

 dorsal lobe, then rising again abruptly toward the inner edge, there forming a lateral saddle more 

 elevated than the slightly evident dorsal saddle, and which joins the suture. 

 This shell differs sufficiently from that represented by de Buch ; but the disposition of its lobes, as well 

 as the identity of its geological position, have decided us to preserve to it the name it has long borne. Its 

 ridges are regularly rounded, and bring it near to G. subnautilinus, to which Beyrich has united it. In 

 the figure given by de Buch, the ridges, obliquely flattened toward the back, render the aperture some- 

 what lanceolate, like that of G. evexus, a species which Beyrich also unites with the preceding. 

 Very common in the slates of Wissenbach. 



3. Goniatites lateseptatus, Beyrich, Beitrage zur Petref., PI. I. f. 1-4. 



This species is very abundant in the roofing-slates of Wissenbach and in the overlying ferruginous 

 limestone of Oberscheld. 



4-. Goniatites Dannenbergii, Beyr., he. cit., PI. I. f. 5. 



This species, found in the slates of Wissenbach, appears to be very rare there. 



.5. Goniatites compressus, Beyr., loc. cit,, PI. I. f. 6. Spirula compressa, Goldf., v. Dechen, Handbuch 

 der Geognosie, von H. T. De la Beche, p. 536. Gyroceratites gracilis, H. v. Meyer. Nova Act. 

 Acad. Nat. Cur. Bonn, tome xv. Part II. p. 59. Id. Bronn. Leth. geog., PL I. f. 6. 



Dorsal lobe small and narrow, lateral lobe scarcely indicated by a slight inflection of the septum. Vo- 

 lutions exposed and often separated, which Beyrich attributes to the disappearance of the shell. 

 From three to four volutions, each presenting fifteen septa. 



Slates of Wissenbach ; very common. 



6. Goniatites retrorsus, de Buch, Ann. Sc. Nat., tome xxix. PI. II. f. 13. Beyr., loc. cit., PL I. f. 10. 

 Tab. nost., PL XXV. f. 2, 2 a, 2 b, and 3, and for varieties a and b, f. 4 and 5. 



Shell nautiloid, inflated, umbilicated ; volutions enveloping, and only showing in the umbilicus the 

 height of the inner edge and the suture. From the edge of the umbilicus to the back the surface 

 of the volutions is inclined, forming a regular curve, which is more distinct in the younger volu- 

 tions. Back limited by two lateral channels which are also deeper in young individuals. Fine and 

 regular striae set off from the suture, rise almost perpendicularly to the edge of the umbilicus, then 

 turn backwards and form an arch which occupies two-thirds of the side and passes into the channel, 

 there describing au inverse curve whose concavity is turned backward : these striae then rise abruptly 

 to the back, which they cover, tracing a deep sinus whose concavity is directed forward. 

 According to Beyrich, the dorsal lobe is small, cyathiform, and as deep as it is wide. Lateral lobe 

 rounded, and twice as deep as the dorsal lobe; its width is equal to its depth. Lateral saddle wide, 

 rounded, reaching the height of the dorsal saddle, and turning a little toward the suture after having 

 passed across half the side. 



Var. a, fig. 4. This shell is distinguished from the preceding by its less inflated form, and by its dorsal 

 channels being less distinct. It forms the passage to the following. 



Var. b, fig. 5. This variety is figured and described by Beyrich. It is still more depressed than var. 

 a; but its striae are similar to those of the shell which we regard as the type of the species, and to those 

 of the first variety. 



We have thought it necessary to describe and figure the G. retrorsus again, because the figure given 

 by de Buch does not agree with his description, and differs also from Beyrich's figure. These two au- 



