of the Carhonifei'ous Period. 129 



Climaxodus imhricatus (M^Coy). 



Tlie only specimen I have access to at present of this species 

 is imperfect at each end^ being 7 lines long, 5|- lines wide at the 

 broad end, and 3 lines wide at the narrow anterior end ; the an- 

 terior portion of the crown is crossed by 7 transverse imbrica- 

 ting ridges in a space of 4 lines, the posterior ones are three- 

 fourths of a line apart, and have a double curvature arising from 

 a small backward wave in the middle, the anterior ones are closer 

 and pass with a slight forward curve across the tooth ; all the 

 imbrications have a backward curve at their extremities, giving 

 them the appearance of lapping round the crown, and all have 

 their free edges directed backwards, so as to resemble a row of 

 Petalodi or other shark's teeth soldered together in the position 

 they usually occupy, one behind the other ; the posterior half is 

 without ridges, the whole crown is slightly convex at the sides 

 and concave in the middle ; the surface is dull and seen by the 

 lens to be finely punctured. 



Rare, in the dark impure limestone overlying the main carbo- 

 niferous limestone of Derbyshire. 



[Col. University of Cambridge.) 



Poecilodus aliformis (M'Coy). 



Sp. Char. Wing-shaped or contorto-subtrigonal, narrow before, 

 broad and subtruncate behind ; inner, straight margin thin, 

 higher in the middle than at each end, the surface seeming- 

 concave from thence to the external oblique margin, which is 

 abruptly deflected, much thickened, rounded, strongly arched 

 downwards at each end, with a slight sigmoidal curve ; this 

 ridge is crossed by seven or eight large, obtusely rounded 

 wrinkles, which become obsolete as they approach the thin 

 inner margin ; surface finely granuloso-punctate under the 

 lens. 



This species most resembles some of the wing-shaped forms 

 of the P. sublavis (Ag.), but the whole tooth is more strongly 

 contorted sigmoidally; the external oblique margin is more 

 thickened, ridge-like and deflected, and above all the great size 

 of the transverse waves or wrinkles easily distinguishes it. The 

 length of a perfect specimen is 1 inch 3 lines, width of the broad 

 posterior end 9 lines, depth of the middle of the external margin 

 4 lines, width of the transverse wrinkles rather more than 1^ line. 



Rare, from the black upper limestone of Derbyshire. 



{Col. University of Cambridge.) 



Poecilodus foveolatus (M^Coy). 



Sp. Char. Longitudinally clavate, depressed, nearly three times 

 Ann. ^ Mag. N. Hist. Ser. 2. Volii. 9 



