﻿ASLKKOLIU'ID.K. 203 



Family ASTEROLEPID^. 



Exoskeleton robust, ornamented with tuberculations of ganoine ; 

 dorsal and ventral shields of trunk firmly united by the lateral 

 plates. Orbits very closely approximated, and the interorbital 

 piece loose. A pair of paddle-like appendages, completely encased 

 in bony plates, articulated by a complex joint with the anterior 

 ventro-lateral plates of the trunk ; median fins not continuous. 



As pointed out especially by Traquair, the dermal plates in the 

 genera of this family are arranged upon one definite plan, and the 

 most satisfactorily known genus, Pterichthys, may be taken as a 

 typical example. This is described in detail under its generic 

 heading (p. 208), and notes on the homologous parts of Bothriolepis 

 are added later (p. 224). 



Synopsis of Genera. 



I. Pectoral appendages shorter than the body- 



armour. 



Anterior median dorsal plate overlapping the 



dorso-laterals Aster olepis (p. 20-3). 



Anterior median dorsal plate overlapping 

 the anterior dorso-lateral, overlapped 

 by the posterior dorso-lateral Pterichthys (p. 208). 



Anterior median dorsal plate in front over- 

 lapping and behind overlapped by the 

 anterior dorso-lateral and the posterior 

 dorso-lateral Microbrachium (p. 223). 



II. Pectoral appendages longer than the body- 



armour. 

 Anterior median dorsal plate overlapping the 

 anterior dorso-lateral, overlapped by the 

 posterior dorso-lateral Bothriolepis (p. 223). 



Genus ASTEROLEPIS, Eichwald. 



[Bull. Sci. St.-Petersbourg, vol. vii. 1840, p. 79 (Astr olepis).] 



Syn. Chelonichthys, L. Agassiz, Poiss. Eoss. vol. i. 1844, p. xxxiii 

 (name only). 

 Odontacanthits, L. Agassiz, Poiss. Foss. V. G. R. 1845, pp. Ill, 



114. 

 (?) Actinolepis, L. Agassiz, ibid. p. 141. 

 (?) Xarcodes, L. Agassiz, ibid. pp. Ill, 115. 



Head and trunk broad, not much elevated, the scutes ornamented 



