548 TELEOSTEI CHAP. 
Pectorals low down, folding like the ventrals. | Post-temporal 
trifid, the upper branch attached to the epiotic, the median to the 
squamosal, the lower to the opisthotic ; post-clavicle large (formed 
of three pieces); scapular foramen between scapula and clavicle ; 
pterygials well developed, two in contact with coracoid. Ventrals 
with 10 to 14 rays. Branchiostegal rays 6 to 14. Air-bladder 
large, not communicating with the ear. 
Elongate fusiform Fishes, covered with large silvery scales 
forming regular longitudinal series; head naked; mouth rather 
small, with thick lips; gill-openings wide. Dorsal fin originating 
in front of ventrals; anal short; caudal well developed, forked. 
soso 
ee 
Fic. 327.—Albula conorhynchus. + nat. size. 
The type of this family, Albula or Butirinus, is remarkable 
among Teleosts in possessing a rudiment of a conus arteriosus to 
the heart, provided with two rows of valvules.' Its single species 
inhabits all the warm and tropical seas. Prof. Gilbert has 
ascertained that the young pass through a metamorphosis, 
analogous to that of the Eels. The “ Leptocephalid” described 
as Hsunculus by Kaup is probably a larval Albula. 
HH 
Fic. 328.—Larva of Albula conorhynchus. (After Gilbert.) 
The deep-sea Japanese Pterothrissus (Bathythrissa) must be 
placed in this family; its skeleton is very similar to that of 
Albula. It differs in the elongate dorsal fin, in the presence 
of small teeth on the maxillary bone, and in the small number 
of branchiostegal rays (6 instead of 12 to 14). 
1 Cf. Boas, Morph. Jahrb. vi. 1880, p. 527, who has found the conus, but in a 
still more rudimentary condition, and with a single row of valvules, in Heterotis 
and Notopterus also. 
