COMPARATIVE STUDY OF SCOMBROID FISHES. 
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six longitudinal grooves are found;—dorsal median, ventral median, and two 
pairs of lateral grooves (figs. 8-12). The vertebral column of Acanthocybiurn 
solandri (figs. 10, 39) and Cybium koreanurn is different from that of the other 
forms in having three lateral grooves instead of two. The first neural spine is 
not always fused to the centrum, nor forms a complete ring at the proximal 
part, for the spinal cord. In the genus Sarda, however, the detachable neural 
spine of the first vertebra forms a complete ring, being fused at the lower end. 
Some anterior neural spines are broad and strong. The other neural and haemal 
spines are slender and weak, and in the middle of the body they unite to the 
centrum of vertebrae almost perpendicularly at least at their insertion (figs. 39, 
41, 42), except in Cybium chinense (fig. 40). They are not compressed laterally. 
The last vertebra is coalesced with the hypural bones and forms a lozenge 
shaped bone, with a small median notch at the posterior margin. Transverse 
processes are not developed, but haemal processes and haemal spines of some 
length are found in many precaudal vertebrae (fig. 38-42). Some of these 
spines are turned anteriorly in Cybium niphonium and Gymnosarda nuda. The 
hypural process of the last haemal spine is notably prominent, and the 
vertebrae in the caudal peduncle are remarkably small, gradually narrowing 
backwards, except in the genera Sarda and Gymnosarda . In these genera 
the hypural process of the last haemal spine is narrow and the vertebrae of 
the caudal peduncle are not modified in size, but in form, becoming quadrate 
prismatic, with their neural and haemal spines broad and flat, as we find in 
the Plecostei. These spines project backward nearly horizontally, and firmly lay 
hold of the succeeding vertebra. In these vertebrae the lateral ridges are 
remarkably developed to the lateral keels (figs. 11, 12). In these cases the 
two vertebrae preceding the last vertebra are small and flattened anteroposte- 
riorly and are capable of lateral movement. The inferior foramen is developed 
in some caudal vertebrae ; but generally it is small and inconspicuous, especially in 
the genus Cybium. In the superior zygapophyses both the anterior and posterior 
pairs are large. In the Scombridae and Cybiidae the haemal canal of precaudal 
vertebrae is suddenly reduced in calibre in some anterior vertebrae. This is 
due to the exclusion of the cardinal vein from the haemal canal. 
In the Plecostei the total number of vertebrae is thirty nine, except in the 
genus Katsuwonus, which lias forty-one vertebrae. The vertebrae are articulated 
