CATALOGUE 
OF 
* ' FOSSIL FISHES. 
PART II. 
Subclass I. ELASMOBRANCHII (continued). 
Order III. ACANTHODII. 
Xotochord persistent; endoskeletal cartilage superficially calcified, 
often granulated. Cranial roof covered with irregular small dermal 
elements, and orbit frequently surrounded by circumorbital plates; 
teeth, when present, firmly fixed to membrane-bones upon the 
ptery go quadrate and mandibular cartilages. Gill-arches each with 
a close series of prominent dermal appendages, probably supports 
for a cutaneous flap. Endoskeletal cartilages of all the fins much 
abbreviated, and the dermal expansion almost or completely desti¬ 
tute of rays; each of the paired fins and most of the median fins 
provided with an anterior spine ; no claspers in the male. Tail 
heterocercal. Dermal armature of trunk consisting of small, closely 
arranged, quadrate granules, which also extend over the greater 
portion of the fins; lateral line passing between two series of the 
granules. 
Synopsis of Families. 
A. One dorsal fin. 
Clavicular bones absent . Acanthodiile (p. 2). 
B. Two dorsal fins. 
Clavicular bones absent . Ischxacanthidje (p. 20). 
Clavicular bones present . Diplacanthidje (p. 22). 
PART II. 
.B 
