DESCRIPTION OF SPECIES 267 



increase in size, and become more irregular in their arrangement, but 

 soon pass above into very regular larger transverse lines, separated by 

 spaces about twice as wide as the lines themselves. These spaces 

 gradually increase in breadth, until they become five or six times as 

 wide as the lines, above which they continue very regular in their 

 arrangement, about four of the lines and three of the intervening spaces 

 occupying a space of 0.10 inch. Near the smaller end, the flattened 

 spaces show what appear to be impressions of septa made visible through 

 the thin shell by pressure. Two of these occupy a space of 0.10 inch. 



"As it is seen in the matrix, the very regular transverse lines on the 

 fossil give it somewhat the appearance of an attenuated Conularia; 

 but as it shows no indications whatever of longitudinal angles or fur- 

 rows, it cannot belong to that genus, from which it also differs in 

 texture, though I am not quite sure that it is an Orthoceras. It will be 

 readily distinguished by its surface markings alone, from any species 

 of the latter genus hitherto described from our Coal-measures. In its 

 surface markings it bears some resemblance to Dentalium cinctum de 

 Koninck (Am. Foss. Belg., PI. XXII, Fig. 3), which Prof, de Konincjc 

 afterwards refers to the genus Orthoceras. Our shell, however, is much 

 more rapidly tapering, and straight instead of arched. 



"Locality and position. Newark, Ohio. Lower Coal-measures." 



Remarks. This species is represented in the collections at hand 

 by three crushed specimens, the most perfect measuring 60 mm. in 

 length and 24 mm. in width at the larger end; the others are fragments 

 evidently from the broad end of much larger specimens. On the most 

 perfect specimen both extremities are incomplete with about three- 

 fourths of an inch missing from the pointed end, so that the minute, 

 crowded, transverse, or annular striae mentioned by Meek cannot be 

 observed. However, with the exception of a few details of surface 

 sculpture at this end, the agreement with Meek's description, in the 

 absence of figures, is so exact that there is little doubt that this is the 

 form to which his description refers. For a distance of one-half inch 

 below the pointed extremity of the specimen at hand, the entire sur- 

 face, including both the striae and the flattened interspaces, is cov- 

 ered by very minute transverse lines which are visible only by close 

 observation under a microscope; on the remainder of the shell these 

 delicate markings have been obliterated. 



Horizon and locality. Lower Mercer limestone: Perry County, 

 Somerset, Locality 35, r; Licking County, Flint Ridge, Localities 47 

 and 49, r. Upper Mercer limestone: Coshocton County, near Warsaw, 

 Locality 72, r. It is probable that Meek's specimen was obtained 

 from Bald Knob, two miles southeast of Newark, Locality 46. 



