2 
ACTINOPTERYGII. 
The feeble development of the vertebral centra suggests the early 
Jurassic age of this fish. As observed by J. Muller, the genus is 
closely related to Thrissops ; but it is distinguished by the characters 
of the vertebrae and the considerably less extension of the anal fin. 
Lycoptera middendorffi, Muller. 
1846. Pholidopltorus macrorhynchus, E. von Eiehwald, Gdogn. d® 
Russie, p. 498 (in Russian, apparently undefined). 
1848. Lycoptera middendorffi, J. Muller, in A. T. von Middendorffi 
Sibirische Reise, vol. i. pt.i. p. 262, pi. xi. tigs. 1-5. 
1868. Lycoptera macrorhyncha, E. von Eiehwald, Lethaea Rossica, 
vol. ii. (Pdriode moyenne), p. 1200, pi. xxxviii. figs. 1-4. 
1868. Lycoptera middendorffi, E. von Eiehwald, ibid. p. 1202, pl« 
xxxviii. figs. 5-7. 
Type. Nearly complete fish; Imperial Academy of Sciences, 
St. Petersburg. 
The type species, attaining a length of about Ol . Length of head 
with opercular apparatus slightly exceeding the maximum depth ot 
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 
Oyprinoid genus A spins (T. R. Jones, Mon. Foss. Estherias, Pal. Soc. 
1862, p. 112). 
Form. # hoc. Lower Jurassic (?) : Turgii, 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. Foss. Estheriae, Pal. Soc. 1862, p. 112), collected at 
luiga by C. G. Austin. One specimen (numbered P. 273 a) 
also displays remains of comparatively" large fins which 
may belong to the genus Belonorhynchus. 
Transferred from Mvs. Practical Geology , 1889' 
P. 1841. Two similar specimens. Egerton Coll- 
P. 6728. Slab exhibiting two imperfect small fishes. 
Presented by Dr. Friedrich Schmidt, 1892. 
