MYKIACANTHIDiE. 
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 Loc. Lower Lias : Lyme Regis, Dorsetshire. 
P. 2081. Type specimen. Egerton Coll. 
Genus CHALCODUS, Zittel. 
[Handb. Palaeont. vol. iii. 1887, p. 72.] 
A genus probably referable to the Squaloraiidae and known only 
by the dentition. Coronal surface of teeth smooth or finely punctate. 
Chalcodus permianus, K. A. yon Zittel, Handb. Palseont. 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 MYRIACANTHIDHh 
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. Foss. vol. iii. 1837, p. 37.] 
Syn. Prognathodus, Sir P. Egerton, Quart. Journ. Geol. Soc. vol. xxviii. 
1872, p. 236. 
Metop acanthus, K. A. von Zittel, Handb. Palseont. vol. iii. 1887, 
p. 110. 
