31 
Semionotus australis, sp. nov. 
PI. VI, Fig. 2. 
Ohs. — A single imperfect specimen, wanting the head and anterior 
portion of the trunk, seems to pertain to a typical species of Semionotns, and 
is shown of the natural size. 
General Form. — The trunk is as deep as in the most typical memhers 
of the genus, the maximum depth l)eing prohahly contained not more than 
three-and-a-half times in the total length ; and tlie tail exhihits the usual 
robust proportions. The dorsal fin is distinctly larger than the anal, though 
scarcely so well-developed ; and this arises opposite a point immediately hehind 
the insertion of the pelvic tins. 
Appendicular Skeleton . — Of the paired tins, only the pclvics are pre- 
served, these being small and consisting of not less than four elongated rays. 
The dorsal fin is evidently in part destroyed hehind, hut exhihits tiftecn rays 
between its origin and a point opposite the origin of the anal; while the 
latter tin, so far as preserved, consists of nine well-sej)arated rays. Tiilcra 
are distinct upon the anterior margin of each of the tins, though relatively 
small and stout, except at the base of the dorsal and caudal ; and all the tin- 
rays arc of the ordinary robust, articulated, and distally-hifiircating type. 
Squamation. — The scales of the anterior portion of the flank are notalily 
deep, many being twice as deep as broad ; and the lateral line was evidently 
well-marked, though the state of preservation of the fossil, exhibiting the 
lateral line of both sides, does not ^lermit of its precise course being traced. 
The dorsal ridge-scales are destroyed. 
Remarks. — In the form of the trunk, this species most nearly 
approaches S. Bergeri* Imt is readily distinguished by the smaller tin-fulcra, 
the less extent of the dorsal tin, and by tlie depth of the principal tlank-scales. 
In the last-named feature it also appears to differ from all otlicr described 
species, except S. Nilssoni, f and this is characterized by a much deeper 
trunk. 
Semionotus tenuis, sp. nov. 
PI. VI, Fig. 3. 
Ohs. — A second well-marked species of Semionotus occurs in the 
Ilawkeshury beds, as indicated by two imperfectly preserved examples, of 
which one is shown of the natural size. 
* See especially J. Strltvcr, Zeitsch. deutsch. geol. Ges., 1SG4, Vol. xvi, pji. .%5-321, I’l. xiii, figs. 1, 3, 4. 
t L. Agassiz, Kech. Poiss. Foss., 1843, Vol. ii, Pt, i, p. 229, PI. xxvii a, figs. 1-5, 
