﻿ICHTHYODORULITES. 115 



P. 2233. JSpine and fragment, the former exhibiting the lateral 

 ornament and anterior keel ; Lower Coal-Measures, Low- 

 moor, Yorkshire. The spine is shown, of natural size, in 



Fig. 9. 



Lepracantkus cold, Owen. Coal-Measures, Kuabon. [P. 2861.] 



Plate I. fig. 1, and a portion of the ornament is enlarged 

 four times in fig. 1 a. Egerton Coll. 



P. 2902. More arched spine ; Lowmoor. Enniskillen Coll. 



Genus NEMACANTHUS, Agassiz. 



[Poiss. Foss. vol. iii. 1837, p. 25.] 



Syn. Desmacanthus, F. A. Quenstedt, Der Jura, 1858, p. 34. 



Dorsal fin-spines of small or moderate size, much laterally com- 

 pressed, nearly straight ; sides of exserted portion marked with fine 

 longitudinal striae, thus not sharply separated from the inserted 

 portion, though exhibiting large, rounded, ganoine- coated tubercles, 

 in longitudinal series, covering a variable extent ; anterior margin 

 prominently keeled ; posterior face with a row of small pointed 

 denticles upon each edge. 



i2 



