f 
2 ACTINOPTERYGII. 
The feeble development of the vertebral centra suggests the early 
Jurassic age of this fish. As observed by J. Miiller, the genus is 
closely related to Thrmops ; but it is distinguished by the characters 
of the vertebrae and the considerably less extension of the anal fin. 
Lycoptera middendorfiPi, Miiller. 
1846. Fholidophorus macrorhynchus, E. von Eichwald, Geogn. de 
Russie, p. 498 (in Russian, apparently undefined). 
1848. Lycoytera middendorffii, J. Miiller, in A. T. von Middendorff’s 
Sibirische Reise, vol. i. pt. i. p. 262, pi. xi. figs. 1-5. 
1868. Lycoptera macrorliyncha, E. von Eichwald, Lethaea Rossica, 
vol. ii. (Periode moyenne), p. 1200, pi. xxxviii. figs. 1-4. 
1868. Lycoptera middendorffii, von Eichwald, ibid. p. 1202, pi. 
xxxviii. figs. 5-7. ^ 
Type. Nearly complete fish; Imperial Academy of Sciences, 
St. Petersburg. 
The type species, attaining a length of about 0*1. Length of head 
with opercular apparatus slightly exceeding the maximum depth of 
the trunk and occupying about one quarter of the total length to 
the base of the caudal fin. Pectoral fins, when adpressed, reaching 
considerably more than half way to the origin of the pelvic pair, 
which arise about midway between the pectorals and the anal; 
dorsal fin with 10 rays, arising immediately behind the origin of 
the anal fin, which comprises 14 rays, the length of the longest 
about equal to the depth of the caudal region at its insertion. 
This fish was erroneously supposed by Egerton to belong to the 
Cyprinoid genus Aspius (T. R. Jones, Mon. Eoss. Estherise, Pal. Soc. 
1862, p. 112). 
Form. ^ Loc. Lower Jurassic (?): Turga, Nertchinsk, Transbaikal 
Province, Siberia. 
P., 273. Six small pieces of shale exhibiting various remains of this 
fish associated with Estheria middendorffii (T. R. Jones, 
' Mon. Eoss. Estherise, Pal. Soc. 1862, p. 112), collected at 
Turga by C. G. Austin. One specimen (numbered P. 273 ct) 
also displays remains of comparatively large fins which 
may belong to the genus Belonorhynchus. 
Transferred from Mus. Practiced Geology, 1880. 
P. 1841. Two similar specimens. Egerton Coll. 
P. 6728. Slab exhibiting two imperfect small fishes. 
Presented by Dr. Friedrich Schmidt, 1892. 
