344 
KAMAKICHI KISHINOUYE : 
interspinous bones are inserted more than posterior ones. In liestrelliger tlie 
interspinous bones carrying finlets have their sagittal wings well developed. 
In tlie Cybiidae the lateral wings of the first dorsal interspinous bone 
gradually narrow towards the dorsal end. The distal segment of the first 
dorsal interspinous bone is a very small round ossicle. Anterior interspinous 
bones are oblique, but those behind the middle of the vertebral column are 
more or less vertical. 
In the Plecostei (fig. 44) the first dorsal interspinous tone is very well 
developed with the lateral wings turned anteriorly, and the anterior sagittal 
wing is very broad, but the lower part not developed, terminating at the 
middle of the lateral wings at the axis. The distal segment in the first dorsal 
is broad and turned over upward, and the dorsal posterior end of the proximal 
segment is also expanded laterally, except a few anterior interspinous bones. 
These expanded parts are turned up, quite like the distal segments. Some posteri¬ 
or interspinous tones of the first dorsal are laterally compressed and want the 
lateral wings. In the second dorsal proper the interspinous bones are com¬ 
pressed anteroposteriorly and tw r o of them are generally found in every myotome, 
instead of one in the first dorsal. In the Carangidae two or three interspinous 
bones are found in one myotome under the first dorsal. In each interspinous 
bone the lateral wings are better developed than the sagittal wings. In the 
second doisal the distal segment is a small narrow tone, inserted between 
the bases of the two moieties of each fin-ray. The exterior margin of 
the lateral wings is strengthened by the development of accessory ridges. The 
interspinous bones of the anal fin differ more or less from those of the second 
dorsal, and resemble rather the first dorsal. The first ventral interspinous 
bone is longer than the succeeding bones, and some anterior ones are fused 
together. Most of them have wide lateral wings but the sagittal wings are 
not w r ell developed. The lateral wings increase in width towards the free end, 
and suddenly converge toward the pointed extremity. TVo of these inter¬ 
spinous bones are found in every myotome. Interspinous bones of the finlets 
are quite alike in the dorsal and anal. They are more or less rod-like in the 
Thunnidae ; but they have lateral as well as sagittal wings in the Katsuwonidae, 
and in the posterior part the sagittal wings only are developed. The distal 
segment of the interspinous bones of the second dorsal and anal is very small, 
