14 SYNOPSIS OF THE CHARACTERS OF THE 



I have not as yet seen the septa of this very rare shell ; the back is broad, bounded by an obtuse 

 angle, from whence the sides are concave, exposing rather more than one half of eacli whorl ; the whorls are 

 about four in number, spirally striated, with rather distant, strong, radiating ribs, forming tubercles when they 

 reach the ridge which bounds the back, where they cease. Diameter one inch, thickness seven lines. 



GONIATITES LATUS. M'Coy. (PL II. fig. 7). 



Sp. Ch. — Globose, back very broad, rounded; mouth transversely elliptical, twice and half as wide as 

 long; umbilicus rounded, angular, very deep, exposing the edges of the preceding whorls ; surface smooth, 

 with a few distant, bent constrictions ; septa, dorsal lobe simple, twice as long as wide, rounded ; dorsal sinus 

 very wide, rounded ; lateral lobe half the length of the dorsal, width equal to the length, acute ; lateral sinus 

 wide, shallow ; surface smooth. 



This is one of the very few Goniatites of the mountain limestone, in which the dorsal lobe is simple, as 

 in those of the inferior rocks, it resembles the G. Nceggerathii, but is much more globose, and has fewer 

 whorls. Diameter one inch three lines, width of mouth ten lines, length of mouth four lines. 



Goniatites Listeri. Mart. sp. 



Ammonites Listeri. Mart. Pet. Derb. — Ammonites Listeri. Sow. Min. Con. — Goniatites Listeri. Phil. Geol. York. 



Sp. Ch. — Spheroidal depressed ; mouth twice as wide as long ; umbilicus very deep, conical, exposing 

 the angle of the internal whorls ; edge of the umbilicus tuberculate ; surface with distinct transverse striae, or 

 ridges, having a shallow, retral wave as they pass over the broad back ; septa, dorsal lobe bifid, dorsal sinus 

 long, acute ; first lateral lobe very large, rounded ; lateral sinus little deeper than the dorsal sinus ; wide, 

 mucronate, or suddenly pointed. 



In this species the umbilicus is so large that all the whorls are half exposed, so that the toothed or plaited 

 edge of the umbilicus can be seen all the way ; the back is broad, slightly convex, and transversely striated. 

 Diameter one and a half inches, thickness one inch. 



Goniatites micronotus. Phil. 



Goniatites micronotus. Phil. Geol. York. 



Sp. Ch. — Discoid, depressed, back rounded; umbilicus very small, rounded; surface with delicate, trans- 

 verse, cm-ved striffi ; septa, dorsal lobe very small, acute, first lateral lobe very large, rounded at the extremity, 

 with their inner edges nearly parallel, dorsal and lateral sinus small and rounded. 



This obscure species is known from the young of G. obtusus and G. striolatus by the small size 

 of the umbilicus, the form of the septa distinguishes it from all the allied species. Diameter one inch, thick- 

 ness six lines. 



Goniatites mutabilis. Phil. 



Goniatites mutabilis. Phil. Geol. York. 



Sp. Ch. — Globose, smooth; innbilicus wide, acute-edged; mouth more than twice as wide as long; back 

 broad, rounded ; constrictions direct. 



One or two specimens of this simply formed shell have occurred ; the septa have not been seen as yet, nei- 

 ther have I seen any specimens corresponding to Professor Phillips's figure of the adult. Diameter four lines, 

 thickness three lines. 



