154 J. W. Davis — Carboniferous Fish-remains. 



were then located in the Florence Court Museum. Amongst others, 

 the large, thick, massive, triangular and convolute teeth from Bristol. 

 They are one and a quarter inch in length and nearly half an inch 

 in thickness ; the surface, convex from back to front, as well from 

 side to side, almost globose. These were named Tomodus convexus. 

 The type specimens are figured in the Trans. Roy. Dublin Society 

 (n.s. vol. i. pi. lv. figs. 15-18). The teeth assigned to the genus 

 Xystrodus are medium or small in size, of a triangular form, much 

 elongated, slightly convoluted, and more or less acutely pointed 

 anteriorly. The crown does not present the bold convexity charac- 

 teristic of Tomodus, but is comparatively flat, one side of the crown 

 being raised, the other depressed. Xystrodus striatus and X. angustus, 

 the Agassizian types, are also figured in the memoir cited above 

 (pis. lv. figs. 7-10 and pi. lv. figs. 19-21). The former was de- 

 scribed by Prof. M'Coy under the name Cochliodus striatus (Brit. 

 Palgeozoic Fossils, p. 624, pi. 31, fig. 27). The group described by 

 Messrs. St. John and Worthen, of which Xystrodus simplex, already 

 mentioned, may be taken as the type, have all the characters of that 

 genus, and appear to be closely related to the British species ; but 

 there is no evidence with which the writer is acquainted which 

 demonstrates that either the British or American representatives of 

 the genus are generically related to Tomodus. 



In recognition of the services rendered to palasontological science 

 by Mr. Parker, I have ventured to distinguish this species by 

 appending to it his name. 



Family Copodontid^e, Davis. 



Genus Mylacodus, Agass. 



Davis, Trans. Eoy. Dublin Soc. n.s. vol. i. p. 480 (1883). 



Mylacodus variabilis, Davis, sp. nov. (Figs. 5, 6, p. 150). 



Teeth trapeziform, length 0-7 inch, breadth 0-9 inch. Crown of 

 at least two different forms, in each the surface is more or less level, 

 slightly convex in central part between the sides, with a sigmoidal 

 curvature in the opposite direction, the posterior and lateral margins 

 are a little raised, inclosing a shallow depression, enamelled, and 

 covered with minute, and in some cases scarcely distinguishable, pustu- 

 lations. Anterior margin of first tooth straight, laterally more or less 

 straight, slightly diverging to the rounded posterior margin. Angles 

 rounded. Second tooth, anterior margin concave ; may have been 

 attached to the posterior margin of the first ; antero-lateral angles 

 acute, not rounded ; lateral margins straight or slightly concave, 

 posterior margin slightly convex, postero-lateral angles slightly 

 rounded. Base not well exposed, mostly hidden in the matrix. 

 Part exposed 0-15 inch in thickness, porous, thinning out towards the 

 margin of the crown, with the upper surface of which it forms an 

 acute angle. 



Two species of Mylacodus have been described in the Trans, of the 

 Royal Dublin Society, both from the Carboniferous Limestone of 

 Armagh, in Ireland ; the types are in the Enniskillen Collection at 



