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



Dublin Society, ser. ii. vol. i. p. 475, pi. Iviii. figs. 19, 20, and 21), 

 in the absence of a prominent lateral border on each side of the 

 coronal surface. In the place of this the borders are more or less 

 depressed, except midway between the anterior and posterior angles, 

 where a minute projection forms an angular prominence. This 

 species in its form appears to hold an intermediate position between 

 the two named above ; whilst its margin and angles are equally 

 regular with those of G. cuneatus, it possesses the elongated form 

 of G. angulatus. 



Family PsAMMODONTiDiE, L. G. de Koninck. 



Genus Psammodus, Agass. 



Davis, Trans. Eoy. Dublin Soc. n.s. vol. i. p. 459 (1883). 



Psammodus rugosus, Agass. 



Poissons Fossiles, vol. iii. p. Ill, pi. xii. figs. 14-18 ; pi. xix. fig. 15 (1833). 



Several teeth of this species have been found : they do not differ 

 from those of other localities, examples of large size are not un- 

 common. A specimen, of which only a portion is preserved, is 1*1 

 inch in breadth, a portion of the length only remains. It differs 

 from the ordinary form in the sigmoidal curvature of the surface of 

 the crown from back to front, one portion being depressed and con- 

 cave, whilst the other is broadly convex, the latter much worn by 

 attrition. The margin of the convex side forms an acute angle with 

 the under surface of the base. 



Genus Pleurodus, Agass. MS. 

 Davis, Trans. Eoy. Dublin Soc. n.s. vol. i. p. 458 (1883). 



Pleurodus Woodi, Davis. 

 Davis, I.e. p. 458, pi. lix. figs. 12-15. 



About a score of teeth of this species have been found. They are 

 extremely interesting because they extend the vertical distribution 

 of the genus downwards from the Yoredale beds of Wensleydale to 

 the thick-bedded Lower Limestone of Derbyshire. The type-species, 

 P. affinis, was obtained from the Coal-measures, and named, but not 

 described, by M. Louis Agassiz. The same author also named a 

 second species, P. Ranhinii, from the Coal-shales of Northumberland. 

 In 1870 a specimen was discovered at Newsham, near Newcastle-on- 

 Tyne, which was described by Messrs. Hancock and Atthey in the 

 Trans, of Northumberland and Durham, vol. iv. pt. ii. p. 408, pi. xv. 

 So much of the fish was preserved that its form could be identified. 

 The length of the head and body was 3 inches, the breadth across 

 the thorax 2 inches. The body was covered with mosaic-like tubercles, 

 the tail was not preserved ; a spine was inserted immediately behind 

 the thorax, five-eighths of an inch in length, laterally compressed, 

 straight, broad at the base, tapering rapidly to a point. The mouth 

 was large, and there were apparently three or four teeth on each 

 ramus of the jaws. The bones were cartilaginous throughout. 



The teeth of Pleurodus Woodi indicate a fish about double the size 

 of the one from the Newsham Coal-shales; and, judging from a 



