48 
Head and Opercular Apparatus. — There is nothing -worthy of remark 
eoneerning the l)ones of the head, few sutnres being distingnishahle. The 
orl)it is large and bordered postero-inferiorly in the nsnal manner with broad 
snhorhitals ; and the slender jaws seem to have been provided with minute 
teeth. The opercular apparatus is equal in width to the posterior snhorhitals ; 
and either the 02 )erculimi or snhoperciilum is at least twice as deep as broad. 
Appendicular Skeleton . — -The paired fins seem to have been very small 
and delicate, for the pectorals arc in every case destroyed, and only traces of 
the pelvic jiair are observed in the type-specimen (PI. Yl, Tig. 4). The 
latter are placed nearer to the anal fin than to the probable insertion of the 
pectorals. The dorsal fin arises very slightly in advance of the anal, with 
eleven rays in the type-specimen ; and the length of the longest anterior ray 
equals half the depth of the trunk at its insertion. The anal fin also exhiliits 
ten or eleven rays, and is evidently at least as elevated as the dorsal, though 
with a shorter liase-line. The caudal fin is not completely preserved in any 
specimen, but it consists of not less than sixteen rays, and was probably 
somewhat forked. In advance of each of the median fins there are slender 
basal fulcra, continued as a very minute fulcral fringe upon the anterior ray; 
and each of the rays is broad and divided at distant intervals by transverse 
joints, while there is usually a distal bifurcation. 
Squamatlon. — The scales are best displayed in an impression shown 
of twice the natural size in PI. VI, Tig. 5. The principal portion of the 
flank is occupied by three deep series, of which the uppermost is traversed by 
the lateral line (PI. VI, Tig. 4), and above and below are two or three small 
scries of nearly equilateral diamond-shaped scales, such as also predominate 
towards the end of the caudal pedicle. 
Remarks. — So far as can be determined from the foregoing description, 
it will be observed that the Australian species only differs essentially from 
the typical Reltopleurus in the single series of deep flank-scales lieing 
represented by three series. In this respect it approaches Rholidophorus, 
and other features also are suggestive of the latter genus. The trunk, 
however, in the species now under consideration is deeper than is usual in 
Rholidophorus, tlie opercular bone already described is most nearly paralleled 
by the operculum of Reltopleurus, and there are ajiparently no large azygous 
scales in front of the median fins, such as characterize Rholidophorus, Y\ c 
therefore venture to assign tlie fish only a provisional generic position. 
