16 
Gen. Conchyliolithus. Fam. NautilitjE. 
Luidii. 
Listcri. 
Hartington, Crongstone, &c. but not common. 
SPECIMEN. 
b. S. Iffive politum, anfractibus internis manifestis distantlbus. Nucleus. 
Obs. This species varies greatly in its superficial markings — In a. the dorsal line is flat, in t. 
somewhat convex or raised, and in both broad and distinctly marked. In c. it is merely a slender 
and scarcely visible seam, in which the lateral strise terminate. The striae on the back and sides 
in a. are sharp, prominent, and somewhat distant from one another — In h. and e. they are very 
qiinute, indistinct, and crow'ded. The disposition of the striae, and of the connecting dorsal lin£» 
as well as the general form of the shell, particularly about the mouth, are, however, the same 
throughout these varieties. To this we may add, that in a number of specimens the varieties are 
readily traced passing into each other ; a sufficient reason for considering them only as one species. 
Spec. b. is the Nucleus or cast this species gives, when the matter, which heretofore supplietl 
the place of the original shell, has been destroyed — ^The interior volutions then become manifest : 
they are small, and form a few distant turns in the inner part of the cast. It may be distin- 
guished from the Nuclei of some other involuted Nautilitx, by its greater breadth at the mouth, 
and by the beak of the outer volution, which is somewhat angular or ridged. 
We should remark, that we have not yet observed the concamerated, or chambered structure m 
this species, necessary to it as a NauHlile : there is little doubt, however, from its general habit, 
but it belongs to that tribe. 
* b. b. * Spirales, anfractibus manifestis, depressis. jdmmonitcs- 
28. Conch. Naut. Ammonites anfractibus extrinsecis teretibus : striis loU' 
gitudinalibus elevatis denticulatis, disci centro pervio, dissepimentis 
integerrimis concavis. 
Tab. 35. Fig. 1, 2. 
Lhwydian Ammonite. 
SeJes: vena metallifera. Tractus vetustus, calcarius. 
% 
Ashford. Very rare. 
Obs. We have only met with one specimen of this fossil — It was found in clay, thrown out of a 
mine in the neighbourhood of Ashford-in-the-JVaters — The substance of the petrifaction was calca- 
rious, but of a softer quality and looser texture than our limestones and spars usually are in Derby- 
shire ; from this, and from our never having yet observed any thing like the species bedded m 
strata, we conclude it to be truly venigenous. 
29. Conch. Naut. Ammonites anfractibus subinsertis, ambitu depresso* 
convexo lato ; costis transversis bifidis, disco craterasformi costato : 
tuberculorum serie marginali, dissepimentis sinuatis. 
