23 
length to the longest ; and there are traces of minute fulcra on the distal half 
of the anterior border thus formed. All the fins are incomplete distally in 
both specimens, but their relative position is shown to be as noted in the 
specific diagnosis. 
Squamation. — The scales form a regular and complete covering, but it 
is uncertain whether they are ornamented. The smaller specimen seems to 
exhibit traces of fine serrations on the hinder margin of some of the flank- 
scales. The scales of the dorsal and ventral regions and towards the hinder 
half of the tail are nearly equilateral, while the principal scales of the flank 
are at least twice as deep as broad. The lateral line is very conspicuous in 
the fossils, and the scales traversed by it are scarcely, if at all, deeper than 
those immediately above and below. 
Affinities. — In many respects this fish is suggestive of the slender 
species of Amblypterus from the Lower Permian of Europe. The discovery 
of satisfactory specimens will therefore be awaited with interest. An 
imperfect fish referred by Eeistmantel to Palceoniscus antipodeus , is 
distinguished from this species by the more remote position of its dorsal fin 
and the smaller size of its scales ; but it doubtless belongs to the same genus 
as the two specimens now described. It may be provisionally named 
Palceoniscus Feistmanteli. 
Family — SEMI0N0TID2E. 
Genus — SEMIONOTUS, Agassiz, 1832. 
(Neues Jahrb. f. Min., 1832, p. 144.) 
Obs. — Two species of this genus have already been recorded from the 
Uawkesbury Formation at Gosford. Another species, evidently new, occurs 
at St. Peter’s. 
Semionotus formostjs, sp. nov. 
Plate IV, Fig. 8. 
Obs. — Besides fragments, there are two important specimens displaying 
most of the specific characters of this fish : — 
(a) The type specimen (PI. IY, Fig. 8), lacking the pectoral fins and the 
greater part of the caudal fin. 
(b) A more imperfect fish, somewhat distorted, with remains of the paired 
fins. 
