





CARBONIFEROUS CEPHALOPODS. 



BY ALPHEUS HYATT. 



The following descriptions, accompanied by figures in outline, were taken 

 from a collection forwarded by Mr. E. T. Dumble, State Geologist of Texas, 

 and other fossils which were in my possession as loans from the National 

 Museum and various persons referred to in the text. These forms being ex- 

 tremely limited in their chronological distribution, and therefore very helpful 

 in distinguishing the age of the rocks in which they are found, it was thought 

 best to have them all published in one treatise. This proceeding also enabled 

 the author to make more satisfactory comparisons, and as these comprise a 

 larger number of species than has yet been got together in a single publica- 

 tion it will be more satisfactory to working geologists. 



NAUTILOIDEA. 



Temnocheilus Conchiferous, n. s. 



Loc. Texas. 



Coll. G-eol. Survey of Texas. 



Figs. 23, 24, natural size. 



This is a small species having an exceedingly thick 

 shell. The sides are decidedly convex and ornamented 

 with short, thick, heavy-looking, fold-like pilse, which 

 are prolongations of the thick, heavy, but not very 

 prominent nodes on the edges of the abdomen. The 

 shell is so thick that in some casts of the interior, as 

 in the figure given above, these nodes are not visible, 

 and in others they are only slightly indicated. The 

 surface appears to have been smooth with the except- 

 ion of these nodes and pilse, but this could not be ob- 

 served satisfactorily. The increase by growth in the 

 transverse diameters is exceedingly rapid, whereas the 

 vertical diameters increase slowly by growth. The 

 abdomen is much depressed, almost flattened along 

 the centre, becoming strongly convex only near the 

 The sides, as in all the species of this genus, converge 



Figs. 23, 24. 

 outer edges or sides 

 very rapidly towards the umbilici 



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