﻿MYRTACANTTHD.aE. 51 



punctate dentine appears to be exposed only in a long 

 narrow band on each of these two elevations. 



Ennislcillen Coll. 



P. 3070. Imperfectly preserved distal portion of dorsal spine, the 

 type specimen of Myriacanthus granulatus. 



Ennislcillen Coll. 



P. 2848. Much broken distal extremity of dorsal spine in hard 

 matrix, the type specimen of Leptacanthus tenuispinus. 



Ennislcillen Coll. 

 43065. Much abraded dorsal spine, wanting the basal portion. 



Purchased, 1871. 

 P. 3072, P. 4454 b-e. Two imperfectly preserved dorsal spines, 

 wanting the basal portion ; also three fragments. 



Ennislcillen Coll. 

 P. 4876. Crushed spine, wanting anterior denticles. 



Purchased, 1885. 

 41382. Distal portion of spine. Purchased, 1869. 



The following specimen is also probably referable to Myria- 

 canthus : — 



P. 2850. Distal portion of dorsal spine, exhibiting a nearly smooth, 

 slender, arcuated extremity, with four widely-spaced, large 

 and downwardly curved posterior denticles, shown, of the 

 natural size, in PI. III. fig. 5 ; Lower Lias, Lyme Regis. 



Enniskillen Coll. 



Genus CHIMiEROPSIS, Zittel. 

 [Handb. Palasont. vol. iii. 1887, p. 113.] 

 Mandibular tooth with an undulating or gently curved oral 

 surface and margin, with an extended, punctate, tritoral area. 

 Presymphysial tooth vertically elongated, bilaterally symmetrical ; 

 the inner aspect flat or concave, the outer aspect convex. Palatine 

 tooth thin, plate-like, triangular, and pointed behind. Vomerine 

 tooth somewhat larger than the palatine, triangular, and pointed 

 anteriorly ; oral surface with an anterior and a posterior punctate 

 tritoral area. Dorsal fin-spine elongated, more or less laterally 

 compressed, and the sides ornamented with tuberculations ; a series 

 of large, thorn-shaped, spinous tubercles arranged along each side 

 of the flattened posterior face, and a single series of similar denticles 

 occupying at least part of the anterior border. Dermal plates 

 tuberculated ; trunk covered with small, conical, radiately grooved 

 granules. {Zittel.) 



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