562 
ACTINOPTEKYGII. 
Family ACRONUllID^. 
Trunk deepened. Maxilla fused with, premaxilla ; incisiform 
teeth in single series. Vertebrae 9 or 10 in abdominal, 13 or 14 
in caudal region. Pelvic bones firmly united ; anal fin with 2 or 3 
spines. Scales minute, more or less ctenoid or spinous. 
Herbivorous, perhaps partly carnivorous, fishes common in tropical 
seas in the neighbourhood of coral reefs. Throe extinct genera 
probably belong to this family, while the existing Acanihurus and 
Naseus seem to date back to the Eocene period, when they ranged 
far north into the present temperate zone. 
Synopsis of Extinct Genera and Genera represented by 
Extinct Species. 
I. No lateral caudal spines ; spinous portion 
of dorsal fin more developed than articu- 
lated portion. 
Scales stellate 
Scales with thickened hinder border bear- 
ing few stout spines 
II. Lateral caudal spines ; spinous portion of 
dorsal fin less developed than articulated 
portion. 
One erectile caudal spine 
One to three (usually two) non-erectile 
caudal spines 
Aulorhamphus (p- 562). 
Apostasis (p. 563). 
Acanthurns (p. 563). 
Naseus (p. 564). 
Genus AULORHAMPHUS, A. de Zigno. 
[Mem. It. Istit. Veneto, vol. xxiii. 1887, p. 19.] 
Syn. Calamostoma , F. Steindachner (non Agassiz, 1833), Sitzungsb- k. 
Akad. Wiss., math.-naturw. Cl. vol. xlvii. 1863, pt. i. ]'• 133- 
An extinct genus comprising small species with much-produced 
snout. Spinous portion of dorsal fin much more developed than 
articulated portion. Scales stellate ; no caudal spines. 
The following species have been described but are not repre 
sented in the Collection : — 
Aulorhamphus bolcensis, A. de Zigno, Mem. It. Istit. Veneto, 
vol. xxiii. (1887), p. 20, fig. 4. Calamostoma bolcensis, 
F. Steindachner, Sitzungsb. k. Akad. Wiss., math.-naturw. 
Cl. vol. xlvii. (1863), pt. i. p. 133, pi. i. figs- 2, 3. Upj? er 
Eocene ; Monte Bolca, near Verona. [The type species- 
imperfect fish ; Court Museum, Vienna.] 
