526 
ACTINOPTERYGII. 
and rostral region wanting. A close series of branchio- 
stegal rays ( hr .) is indicated on the side figured, while the 
large dimensions of the preoperculum are shown by the 
counterpart. The vertebral centra are longitudinally 
split, but their appended arches are well exhibited, and 
intermuscular bones are very numerous in the dorsal part 
of the abdominal region. The relative proportions of the 
paired fins are indicated by fragments, and the slender 
proximal ends of the pair of pelvic fin-supports can be 
seen. The median fins are imperfect, but the origin of 
the dorsal fin is observed to be opposite that of the anal 
r 
fin, the former displaying about 12 rays and the latter at 
least 25 rays, of which only the basal ends and supports 
remain. The lower caudal lobe is perfect in the counter¬ 
part, from which it is restored in the figure; the articular 
dividing lines exhibit the characteristic step-like arrange¬ 
ment. Presented by F. Harford , Fsq., 1888. 
Thrissops microdon, Heckel. 
1849-50. Chirocentrites microdon, J. J. Heckel, Sitzungsb. k. Akad. 
Wiss., matk.-naturw. Cl. 1849, pt. i. p. 18, and Denkschr. k. Akad. 
Wiss., math.-naturw. Cl. vol. i. p. 209, pis. xvi., xvii. 
1856. Thrissops microdon , J. J. Heckel, ibid. vol. xi. p. 243. 
1863. Chirocentrites microdon , A. Wagner, Abh. k. bay. Akad., math.- 
pkys. Cl. vol. ix. p. 734, footnote. 
1879. Thrissops microdon , F. Bassani,Verkandl. k. k. geol. Reichsanst. 
p. 163. 
1882. Thrissops microdon , F. Bassani, Denkschr. k. Akad.Wiss., math.- 
naturw. Cl. vol. xlv. p. 208, pi. iii. 
Type. Head aDd abdominal region ; Court Museum, Vienna. 
A species attaining a length of about 0*45. Length of head with 
opercular apparatus about equalling the maximum depth of the 
trunk, and contained seven times in the total length of the fish. 
Vertebrae at least 60 in number, about 33 being abdominal and 27 
caudal. Pelvic fins nearly twice as distant from the pectorals as 
from the anal; dorsal fin, with about 14 rays, arising opposite the 
middle of the anal, which is much elevated in front and comprises 
nearly 40 rays ; caudal fin very deeply forked. 
Form. Log. Cretaceous : Isle of Lesina, Dalmatia. 
P. 7451. Imperfect fish wanting the region behind the origin of the 
anal fin. Purchased , 1895. 
