196 On some new Oarhoniferous Limestone Fossils. 



Orthoceras [Cydoceras) Flemingi (M'Coy). 



Desc. Very gradually tapering ; section (? broad oval), siphon 

 subcentral large, slightly excentric; septa numerous, mode- 

 rately convex, one coinciding with each of the external rings. 

 Surface girt with close, obtuse, prominent, transverse rings, 

 little more than their own diameter apart, undulated by about 

 fourteen or fifteen strong longitudinal costal, slightly further 

 apart than the transverse rings, so that the oblong intervening 

 spaces are wider than long, and nearly equalling them in 

 thickness, both transverse rings and intervening spaces marked 

 by strong transverse imbricating striae, six or seven between 

 the centre of one transverse ring and the next. A specimen 

 5 lines long and 2 lines in diameter at the smaller end has 

 twelve rings. 



This species can only be confounded with the O. (C.) rugosum 

 of riem., from which it is distinguished by its much more nu- 

 merous and closer rings, fewer and larger longitudinal costse, 

 stronger transverse striae, and large siphon far removed from the 

 margin. 



Very rare in the carboniferous limestone of Lowick, North- 

 umberland. 



[Col. University of Cambridge.) 



Orthoceras {"f Poterioceras) comu-vaccinum (M'Coy). 



Desc. Conical, rapidly tapering to an obtusely rounded point, 

 very slightly arched ; section perfectly circular throughout ; 

 septa very oblique, flattened, slightly convex, moderately ap- 

 pi'oximate, extending much further forward on the inner side 

 of the general curve than on the outer or convex aspect, the 

 lateral edges being very slightly sigmoidal, on account of their 

 obliquity ; the septa are broad oval in form, the longest dia- 

 meter being in the antero-posterior direction; siphon large, 

 about its own diameter within the outer edge (corresponding 

 with the convexity of the general curve of the shell). Surface 

 horny in appearance, marked with irregular scratch-like lon- 

 gitudinal markings, and fine, nearly regular transverse im- 

 pressed lines, separated by rather wider flattened spaces; 

 thirteen transverse striae in 2 lines at an inch and a quarter 

 in diameter, about twenty in the same space at 9 lines in dia- 

 meter. Length of average specimen 5 inches 9 lines, 2 inches 

 3 lines in diameter at the anterior end, and regularly tapering 

 to the obtusely pointed apex in the above length; average 

 distance of the last few septa 2 lines. 



The above measurements are of average-sized specimens, 



