﻿MTRIACANTHID^. \ v? 43 



Squaloraja tenuispina, A. S. Woodward. 



1886. Squaloraja tenuispina, A. S. Woodward, Proc. Zool. Soc. p. 530, 

 pi. lv. fig. 6. 



Type. Detached rostral spine ; British Museum. 

 A small species known only by the rostral spine, which is slender 

 and extremely acuminate. 



Form. Sf Log. Lower Lias : Lyme Regis, Dorsetshire. 



P. 2081. Type specimen. Egerton Coll. 



Genus CHALCODUS, Zittel. 



[Handb. Pakeont. vol. iii. 1887, p. 72.] 



A genus probably referable to the Squaloraiidse and known only 

 by the dentition. Coronal surface of teeth smooth or finely punctate. 



Chalcodus permianus, K. A. von Zittel, Handb. Palaeont. vol. iii. 

 (1887), p. 72, woodc. fig. 66. — Kupferschiefer ; Gliicks- 

 brunn Thuringia. [Associated dental plates ; Palseonto- 

 logical Museum, Munich.] The type and only known 

 species. 



Family MYEIACANTHIDJE. 



Body elongated ; anterior dorsal fin above the pectorals, provided 

 with a long, straight, robust spine. Teeth forming two (? or three) 

 pairs of thin dental plates in the upper jaw, the hinder pair atten- 

 uated mesially and not closely apposed in the median line ; lower 

 dentition consisting of a pair of large dental plates, meeting at the 

 symphysis, and a median incisor-like tooth in front. A few dermal 

 plates present upon the head. Males with a large prehensile spine 

 upon the snout. 



Synopsis of Genera. 



Palatine teeth larger than the vomerine Myriacanthus (p. 43). 



Palatine teeth smaller than the vomerine Chimceropsis (p. 51). 



Genus MYRIACANTHUS, Agassiz. 

 [Poiss. Poss. vol. iii. 1837, p. 37.] 



Syn. Prognathodus, Sir P. Egerton, Quart. Journ. Geol. Soc. vol. xxviii. 

 1872, p. 236. 

 Metopacanthus, K. A. von Zittel, Handb. Paleeont. vol. iii. 1887, 

 p. 110. 



