COJIPAKATIVE STUDY OF SCOMHROID FLSHE«. 409 



loriimen between the bnsioceipital and p irasplienoid is small and opens nearly 

 ill a horizontal plane. Piiroccipital condyles touch each othei' at the median 

 line, and the (X'oipital condyle is only slightly concave. Number of veiiebrae 

 is 31-C4, generally more than forty, and varies greatly even among closely 

 allied species. Ixelative number of the caudal and precaudil vertebrae is also 

 variable. DilTerentiation of vertebrae is a httle more advanced tiian in the 

 Seombridae. Sometimes I found abnormal cast« iu wliicli two or more 

 vertebrae fused together. Longitudinal gro jves in vertebrae are deep, and 

 thus the cross-section of most vertebrae show a six-radiatiug figm-e (figs. 

 8-12j. In some posterior precaudal vertebrae a short haemal process is found. 

 Neural pi'ocess is broad in some antarior prtxjaudal vei'tebnie, and the process 

 of the first vertebra is free from the centrum. The last caudal vertebra is 

 consohdated with the hypural banes, jind forms a fan-shaped bone with a 

 notch at the median posterior comer. Hypuml spine very prominent, but 

 rather small in Sarda and Oymnosardu. One or two auxiliary intermuscuLir 

 bones are found iu the occipital region, where the clavicular ligament is 

 inserted. Intermuscular bones are weakly developed at the anterior portion of 

 the l)ody only, connected by a few and poor tendons. 



Gill-rakers are very pjorly developed in the Cybiidae. They are short, 

 not much comprassad, generally a little more than ten in number, and entirely 

 absent iu ArantlidCijUimi. A few gill-rakers are found near the angle of the 

 second branchial arch in some forms. Two or more rows of short denticles are 

 found on the inner side of gill-rakere. Ribs are found on the dorsal wall of 

 the body-cavity, as myotomes are bent with acute angles. Pelvic girdle narrow 

 and elongated. Generally the lower piece of the poslclaviclc is nearly straight. 

 The vascular system of the Cybiidae has many characteristics : — develop- 

 ment of the renal portal system from dorsal segmental veins in the precaud- 

 al region, origüiation of the genital artery from the dorsal aorta, remarkable 

 separation of the doi-sal aort.i from the cardinal vein with the inter\ontiüu 

 oi rete mirabilis of the renal portal system between them. Ureters of both sides 

 ai'e entirely separated. Kidneys elougiited. Muscles nearly colourless, but the 

 median superficial Literal poiiion is i-eddish. Tliis reddish portion becomes 

 rather thick joosteriorly (fig. 17). 



The posterior side of the preopercle is generally a Httle concave in Cijbium 



