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Genus AETHALION, Miinster. ntc . fi e^'O T kM r 
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S-lli . ,: [Neues Jahrb. 1842, p. 41.] Serv. 0*2$, Z^ 7 *- 
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Maxilla arched, with a slightly convex dentigerous border; man- 
0 >dible scarcely prominent, and dentary gradually deepening from 
/\chc\ /£. Sift. • the symphysis backwards without any marked thickening; teeth 
Sti&Jz- £'£/_. minute and closely arranged. Opercular apparatus as in Leptolepis. 
Vertebral centra strengthened by delicate longitudinal ridges of 
secondary ossification. Dorsal fin opposed to the space between 
the pelvic pair and the anal, the latter comparatively small and not 
extended; caudal fin deeply forked, No enlarged or thickened 
ridge-scales. 
/4 V Aethalion knorri (Blainville). 
1755. Figure by G. W. Knorr, Samrnl. Merkwiirdigk. Natur, pi. xxx. 
fig. 2. 
1818. Clupea knorri, H. D. de Blainville, Nouv. Diet. d’Hist. Nat. 
vol. xxvii. p. 331. 
1839. Caturus cmgustissimus, G. von Miinster, Neues Jahrb. p. 679. 
[Imperfect fish; Palaeontological Museum, Munich.] 
1842. Aethalion infiatus, G. von Miinster, ibid. p. 42. [Ditto, counter¬ 
part in British Museum.] 
1842. Aethalion angustissimus, G. von Miinster, Beitr. Petrefakt. 
pt. v. p. 60, pi. v. fig. 3. [Imperfect fish; Palaeontological 
Museum, Munich.] 
1844. Leptolepis crassus, L. Agassiz, Poiss. Foss. vol. ii. pt. ii. p. 131, 
pi. lxi. a. fig. 5. [Imperfect fish ; Erlangen Museum.] 
1861. Aethalion angustissimus, T. C. Winkler, Descript. Poiss. Fors. 
Solenhofen (Natuurk. Verhandl. Holland. Maatsch. [2] vol. xiv.), 
p. 40, fig. 6. 
1861. Aethalion injlatus, T. C. Winkler, ibid. p. 42, fig. 7. 
1861. Aethalion tenuis, T. C. Winkler {errore), ibid. p. 44, fig. 8. 
1863. Aethalion blainvillei, A. Wagner, Abh. k. bay. Akad. Wiss., 
math.-phys. Cl. vol. ix. p. 728. [New name.] 
1863. Aethalion crassus, A. Wagner, ibid. p. 730. 
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Type. Nearly complete fish. 
The type species, attaining a length of about 0*2. Length of 
head with opercular apparatus much exceeding the maximum depth 
of the trunk, and contained somewhat more than four times in the 
total length of the fish. Vertebrae 50 in number. Dorsal fin with 
about 15 rays, arising at the middle point of the back; pelvic 
fins arising immediately in advance of the dorsal, but slightly 
nearer to the anal than to the pectorals ; origin of anal fin, which 
has about 10 rays, midway between the pelvic and caudal fins. 
