FISH OF THE CARBONIFEROUS PERIOD. 23 



the oblique striation crossing the ordinary punctuation of Psam- 

 modontoid teeth is a character I have not seen in any other 

 tooth. Height of crown 6 hnes, width of base 5 lines, depth of 

 root 4 lines. 



From the carboniferous limestone of Armagh. 



{Col Capt. Jones, R.N.) 



Glossodus marginatus (M'Coy). 



Sp. Char. Crown about one-third higher than wide, having a 

 slight antero-posterior sigmoidal curve ; thickness, from before 

 backwards, little more than one-fourth of the width ; lateral 

 margins subparallel, prominent on the posterior face, which is 

 gently concave in the middle ; apex narrowed, rounded, curved 

 backwards ; surface glossy, finely punctured, marked towards 

 the tip with minute anastomosing longitudinal wrinkles ; a few 

 obtuse plicse. Length of crown 5 lines, width 3 lines. 



Easily distinguished from the G. marginatus by its more 

 finely punctured, glossy surface, rounded tip and prominent 

 lateral margins. 



One of the rarest fossils of the carboniferous limestone of 

 Armagh. 



{Col. University of Cambridge ; I think T have seen another in 

 that of Capt. Jones at Dublin.) 



Climaxodus (M^Coy), n. g. 



(Etym. Kklfjua^, a flight of steps, and 6Bov<;, a tooth.) 



Gen. Char. Tooth longer than wide, gradually narrowing towards 

 the front with nearly straight sides ; anterior part of the crown 

 crossed by broad, imbricating, transverse ridges at right angles 

 to its length ; surface minutely punctured. 



The above generic name has reference to the remarkable step- 

 like character of the ridges which cross the anterior part of the 

 tooth at regular intervals. The broad posterior part of the tooth 

 is without ridges and resembles a Psammodus. In the fact of 

 being as it were small, ridged Psammodi, those teeth are allied 

 to the genus Poecilodus, but all the true Poecilodi are inequilateral, 

 mussel-shaped teeth, consequently placed in pairs in the mouth, 

 and have the ridges oblique ; the Climaxodi, on the contrary, are 

 equilateral, and were therefore most probably mesial in position, 

 and the ridging is transverse. 1 am aware of one species in the 

 Armagh limestone and the following. I think it possible that 

 the so-called Poecilodus parallelus (Ag.) may ultimately be re- 

 ferred to this genus, as it differs from the true Poecilodi in some 

 at least of the above characters. 



