NOTIDANIDjE. 
157 
Suborder II. JSTEROSPONDYLI. 
Vertebrae, when fully developed, having the radiating calcified 
laminae predominating over the concentric laminae (asterospondyUc, 
Hasse). Specialization resulting in no marked depression of the 
body, and the pectoral fins never growing forwards towards the 
head ; spiracles of small size, almost or quite absent in the most 
specialized forms. Anal fin present. 
Division A. — A single dorsal fin present ; gill-clefts more 
than five in number. 
Tho following primitive family is provisionally placed here, its 
distinctive subordinal characters being not yet very evident, but its 
relationships being ob-viously closer with the Cestraciontidae than 
with any other hitherto recognized family. 
Family NOTIDANID.F. 
Single dorsal fin, without spine, remote; caudal fin large. No 
nictitating membrane ; gill-clefts 6-7 : spiracles small. Teeth 
with sharply-pointed coronal cusps, several scries simultaneously 
functional. 
Genus NOTIDANUS, Cuvier. 
[Ri'gne Animal, vol. ii. 1817, p. 128.] 
Syn. Heptranchias, C. S. Ilafinesque Schmalz, Caratt. Nuovi Gen. 
Anim. Sicilia, 1810, p. 13. 
JIe.ranchus, C. S. Rafinesque Schmalz, op. cit. p. 14. 
Monoptertdnus, II. D. de Blainville, Hull. Soc. Philom. 1816, 
p. 121 fin part). 
AeUopos, L. Agas.siz, Roiss. Foss. vol. iii. 1843, p. 376 (in part). 
Xiphodolamia, J. Leidy, Journ. Acad. Nat. Sci. Philad. [2] vol. viii. 
1877, p. 262. 
Body moderately elongated ; mouth inferior ; gill-openings six 
or seven, without flaps of skin. Principal teeth consisting of a 
series of compressed cusps fixed upon a long base ; all the cusjis 
inclined in one direction, the anterior larger than tho others, with 
or without small denticles at its base in front. Anterior teeth of 
the upper jaw clustered, awl-shaped ; a median symphysial series in 
