500 
ACTINOPTERYGIl. 
Type. Imperfect fish. 
The type species, attaining a length of about 0T5. Length of 
head with opercular apparatus equalling about three quarters of 
the maximum depth of the trunk and one third of tho total length 
of the fish to the base of the caudal fin. Fourth to sixth dorsal 
spines longest ; second anal spine largest and stoutest, equalling 
the third dorsal spine. 
Form. Sf Loc. Upper Cretaceous (Montian) : Mont Aime, Marne. 
28291. About 15 specimens, large and small, showing all the 
principal characters of the genus and species. 
Purchased , 1851. 
P. 1914. Fine small specimen, displaying the serration of the 
anterior suborbital and preoperculum, also the delicate 
pectoral fin. Egerton CoV. 
Genus ACANUS, Agassiz. 
[Poiss. Foss. yoI. iv. 1838, p. 4'.] 
Trunk laterally compressed and deeply fusiform. Articulation 
of mandible not behind middle of orbit; preoperculum finely 
pectinated. Vertebra; 10 in tho abdominal, 13 in the caudal 
region. Dorsal fin continuous, with 10 very large ribbed spines 
and about 12 comparatively small articulated rays ; anal fin with 
3 large ribbed spines and about 13 articulated rays ; caudal fin 
truncated or slightly forked. [Scales unknown.] 
An extinct Oligocene genus. 
Acanus spinosus (Blainville). 
1818. Zeus spinosus, H. D. de Blainville, Nouv. Diet. d'Hist. Nat. vol. 
xxvii. p. 317. 
1838-39. Acanus ovalis, L. Agassiz, Poiss. Foss. vol. iv. pp. 5, > 
pi. xvi. fig. 1 . [Imperfect distorted fish ; Carlsruhe Museum ] 
(?) 1838-39. Acanus minor, L. Agassiz, ibid. pp. 6, 127, ph xv ‘- 
[Fragmentary fish ; Berne Museum.] 
1886. Acanus longispina, A. Wettsteiu, Fischfauna Tertiaer. Glarner 
Bchief. (Denkschr. schweiz. Palaeont. Ges. vol. xiii.), p- *>o, pb 1U - 
figs. 1, 2, 3, 9. 
Type. Imperfect distorted fish. j. 
The typo species, attaining a longth of about 0'5. Depth o 
trunk at end of abdominal region about equal to length ot can; ,l 
vertebra. Of tho dorsal fin-spines only tho two foremost smaller 
1 This name first appeared without definition in Neuc9 Jalirb. 1834, P- 3®' 
