Miscellaneous. 107 
the hind lobe of a Chelonian plastron from the Wealden, which was 
remarkable as showing a median row of epidermal shields. The 
name of Archwochelys valdensis was proposed for the form so repre- 
sented. The new generic term Hylaochelys was also proposed for 
the Purbeck Chelonian described by Sir R. Owen as Plewrosternuim 
latiscutatum, and was also taken to include some other forms from 
the Wealden. 
The second section of the paper treated of the affinities of Plewro- 
sternum. It was concluded that Digerrhwm, Cope (as represented by 
the so-called Platemys Bullockz), is identical with Pleurosternum, of 
which there appears to be only one Purbeck species. Evidence was 
brought forward to show that in the adult of Pleurosternum the 
pubis had a facet for articulation with the xiphiplastral ; and it was 
proposed to refer this genus, together with Platychelys and Baéna, 
to a new section termed ‘“‘ Amphichelydia,” which was regarded as 
allied both to the true Cryptodira and to the Pleurodira. 
MISCELLANEOUS. 
Triassic Fish-scales from Siberia, By A. Smita Woopwaxrp. 
So little is known of the paleontology of Siberian formations that 
a recent memoir by Dr. J. V. Rohon* upon some fragmentary 
remains of fossil fishes from the Upper Yenisei is of considerable 
interest and importance. ven detached scales and bone-fragments 
are worthy of discussion when obtained from such a source; and 
among other fossils the author describes some unsatisfactory speci- 
mens of this character from an undetermined horizon near the village 
of Kubekowa. These fossils, however, do not appear to have been 
sufficiently compared with known forms elsewhere. The scales 
named Paleoniscus sibiricus (loc. cit. p. 12, figs. 22, 28) are so closely 
similar to those of the Lepidotoid Ganoid Colobodus + that they may 
be assigned with much probability to this genus ; another fragment 
(loc. cit. fig. 21) is sculptured like some of the head-bones of Colo- 
bodust; and the associated ring-vertebree (Joc. cit. figs. 23, 29) may 
well pertain to the same fish, whereas they indicate a higher stage 
of development of the axial skeleton than has hitherto been observed 
in any of the Paleoniscide. Colobodus has only been recorded as 
yet from the European Muschelkalk and Lettenkohle, in which it 
is widely distributed ; and the undetermined horizon of C. sibiricus 
may thus be provisionally regarded as Triassic. 
* J. V. Rohon, “ Ueber fossile Fische vom oberen Jenissei,’” Mém. Acad. 
Ip. Sci. St.-Pétersbourg, [7] vol. xxxvi. no. 13 (1889). 
1 Cf. especially W. Dames, Palzont. Abhandl. vol. iv. (1888), pl. xvia. 
figs. 6-8. 
a: Cf. W. Dames, zbid. pl. xiv. fig. 1. 
