CHAPTER XV 
BERYCOIDEI 
HE Berycoid Fishes.— We may place in a separate 
order a group of fishes, mostly spiny-rayed, which 
P| appeared earlier in geological time than any other 
otf the spinous forms, and which in several ways represent the 
transition from the isospondylous fishes to those of the type of 
the mackerel and perch. In 
the berycoid fishes the ventral 
fins are always thoracic, the 
number of rays almost always 
greater than I, 5, and in all 
cases an orbitosphenoid bone 
is developed in connection 
with the septum between the 
Fic. 198.—Skull of a Berycoid fish, Beryx orbits above. This bone is 
splendens Cuv. & Val., showing the or- found in the Isospondyli and 
bitosphenoid (OS), characteristic of all see i 
Beryeatd fishes. other primitive fishes, but ac- 
cording to the investigations 
of Mr. E. C. Starks it is wanting in all percoid and scombroid 
forms, as well as in the Haplomi and in all the higher fishes. 
This trait may therefore, among thoracic fishes, be held to define 
the section or suborder of Berycordet. 
These fishes, most primitive of the thoracic types, were more 
abundant in Cretaceous and Eocene times than now. The 
possession of an increased number of soft rays in the ventral 
fins is archaic, although in one family, the AM/onocentride, the 
number is reduced to three. Most of the living Berycotdet 
retain through life the archaic duct to the air-bladder char- 
acteristic of most abdominal or soft-rayed fishes. In some 
however, the duct is lost. For the first time in the fish series 
the number of twenty-four vertebree appears. In most spiny- 
250 
