SEMIOXOTIDZE. 
157 
P. 5455 a. Imperfect head with opercular apparatus, and fragment 
of trunk with pectoral fin, described and figured ibid. 
p. 141, pi. vi. fig. 7. 
Presented by Hugh Exton , Esq., M.D ., 1888. 
The imperfectly known genus Dipteronotus (Egerton, Quart. 
Journ. Geol. Soc. vol. x. 1854, p. 369) appears to be closely related 
to Cleithrolepis , hut is distinguished at least by its much-elongated 
dorsal fin, which is broken in the type specimen, and was originally 
described by Egerton as double. A single species, D. cyjohus, is- 
determined by Egerton (Joe. cit. p. 369, pi. xi.) from the Keuper of 
Bromsgrove, Worcestershire, the type and only known specimen 
being now preserved in the Museum of Practical Geology, London. 
C* €? A vy <2/2 
Genus AETHEOlsEPIS, A. S. Woodward. 
[Described in forthcoming Mem. Geol. Surv. A.8. Wales, 
Palaeont. no. 9.] 
Trunk deep and laterally compressed. Head small, and external 
bones more or less tuberculated. Notochord persistent, apparently 
without ossifications in the sheath. Ein-fulcra well developed. 
Pectoral fins placed laterally; pelvic fins of moderate size; dorsal 
and anal fins extended, acuminate in front, and both remotely 
situated; [? caudal fin not forked]. Scales of abdominal region 
thick, much deeper than broad on the flank, quadrate in form, 
deeply overlapping, with large peg-and-socket articulation, and an 
anterior inner longitudinal keel; the scales of this form gradually 
passing into those of the caudal region, which are very thin, deeply 
imbricating, and more or less oval in shape. Scale-ornament con¬ 
sisting of tubercles. 
Aetheolepis mirabilis, A. S. Woodward. 
1893. Aetheolepis, A. S. Woodward, Natural Science, vol. iii. p. 449, 
woodc. [Described in forthcoming Mem. Geol. Surv. N.S. Wales, 
Palaeont. no. 9.] 
Tyqoe. Nearly complete fish; Museum of Geol. Surv. N.S. Wales, 
Sydney. 
The type species, attaining a length of about 0*17. Length of 
trunk from the pectoral arch to the base of the caudal fin equalling 
scarcely more than three-quarters of the maximum depth; the 
dorsal margin gibbously curved, the ventral margin more regularly 
arched. Head with opercular apparatus occupying slightly more 
than one-quarter of the total length of the fish to the base of the 
