452 
AOTIlfOPTEKYGII. 
varied as those of the existing Isospondylous family Mormyrid®. 
The more elongated and degenerate types are those inhabiting great 
depths. 
All the known fossil Scombrid® occur in marine deposits. 
Synopsis of Extinct Genera and Genera represented by 
Extinct Species. 
I. Trunk fusiform. 
A. Two dorsal fins close together. 
Posterior dorsal and anal fins much ex- 
tended, perhaps without finlets . . Isurichthys (p. 453). 
Posterior dorsal and anal fins short and 
deep, with 8 to 12 finlets Thynnus (p. 454). 
[Skull resembling that of Thynnus, 
but deeper in proportion to its 
w idth Eothynnus (p. 457).] 
B. Two dorsal fins well separated. 
Teeth very small and conical ; about 30 
vertebra} ; caudal pedicle without 
lateral keel ; paired fins small ; no 
enlarged pectoral scales Scomber (p. 459). 
As Scomber, but with nearly 40 verte- . 
brae and larger pectoral fins .... Palimphyes (p. 460). 
[Skull resembling that of Scomber, but 
with larger teeth Scombrinus (p. 461).] 
As Scomber , but caudal pedicle with 
lateral keel and pectoral scales 
enlarged Auxis (p. 463). 
Marginal teeth large and laterally com- 
pressed, in single series ; caudal 
pedicle with cartilaginous lateral 
keel Cybium (p. 465). 
[Skull resembling that of Cybium, but 
shorter and without median fron- 
tal crest Eoccelopoma (p. 470).] 
[Jaws as in Cybium, but teeth round or 
ovoid in section Sphyrcenodtis (p. 473).] 
[Jaws as in Sphyreenodus, but small 
teeth on dentary outside series of 
large teeth Scombramphodon 
II. Trunk much elongated. (p. 474).] 
Paired fins small ; finlets behind dorsal 
and anal fins Thyrsitocephalus 
Pelvic fins rudimentary ; dorsal fins (p. J?6). 
continuous ; no dorsal or anal 
finlets Lepidopus (p. 477). 
1 G. A. Boulenger, Proc. Zool. Soc. 1898 (1899), p. 780. 
