CATALOGUE 
OF 
FOSSIL FISHES. 
Class PISCES. 
Subclass I. ELx\SMOBRANCHII. 
Skeleton cartilaginous, membrane-bones absent (? except rarely, 
ill-defined). Mandibular suspensorium articulated with the cranium ; 
gill-clefts separated, without external cover. Exoskeleton, when 
pre.sent, structurally identical with the teeth. In the living forms 
— optic nerves not decussating, bulbus arteriosus of the heart with 
three series of valves, intestine with a spiral valve, and ovaries with 
few large ova. 
Order I. ICHTHYOTOMl. 
Endoskcletal cartilage permeated throughout with granular calci- 
fications. Notochord rarely or never constricted ; calcifications of 
the sheath arrested at the most primitive “ rbacbitomous ” stage, 
except in the caudal region. Neural and haimal arches and spines 
long and slender ; no intercalary cartilages. Pectoral fins with long 
segmented axis (“ archipterygial ”). 
Family PLEURACANTHIDiE. 
Body slender, but slightly depressed ; mouth terminal ; tail diphy- 
cercal. Dorsal fin elongate, low, continuous along the back from a 
point shortly behind the head ; slender interneural cartilages more 
numerous than the neural spines. Pectoral fin with biserial arrange- 
ment of cartilaginous rays. 
4 B 
