COMPARATIVE STUDV OF SCOMBROID FLSttES. 353 



large masses of rete mirabilis of blood-vessels are found. In ParcUhunnus the 

 external surface of the liver Las a few short venules near the posterior nmrgin ; 

 but in Kcothnmius no venules are found at the external surface. In these two 

 genera the lobes of the liver are not deeply cut, and in the latter gumw the 

 right lol)e is a httle longer tliau the other lobes. In Eiilhymms and Auxis 

 (fig. 2) tlie right lobe of tbe liver is enormously elongate*!, almost reaching the 

 anas, while the left lobe is often inconspicuous, being not separate"" _ a distinct 

 iudenfaition fi-om tiie middle IdIkj. In Auxis moreover dark and thick dendritic 

 figures of the hepitic vein are clearly discernible on the external surface of the 

 liver. 



Tlie gall-bladder (figs. 1-3, 5, 6) is an enormously elongated sac, running 

 along the intestine, on the inner side of the right lobe of the liver. The 

 bladder becomes narrow at tlie anterior part and jjasses gradually to the cystic 

 duct which is bent backwai'd along the inner side of the middle lobe of the 

 liver, and opens to the duodenum with a narrow duct, ductus choledochus. To 

 the cystic duct three or more hepatic ducts open. These are more or less den- 

 dritically branched in the liver. In the Scombridae the gall-bladder is elon- 

 gated and receives some slender ducts (3 in Scomber japmicus). In the Ka- 

 tsuwonidao the hepatic duct in the right lote of the Hvei" is vciy long, running 

 the whole length of the lob<3. The gall-bladder is greenish in colour, but it 

 is sometimes purplish in a stale fish. 



The spleen (figs. 1-3, 5, 6) is a compact, elongated IxxJy, more or less 

 compressed, and dark red or brownish in colour. It generally lies close to the 

 junction between the duodenum and the small intestine. It is rather small in 

 the Scombridae aud Cybiidae, but in the Thunnidae it is very well developed 

 and is attached to the anterior part of the fold of the small intestiue, occupy- 

 ing the space enclosed by the duodemuu, aud the intestinal tract to the second 

 bend. In the Katsuwonidae the spleen is again small aud lies exterior to the 

 intestine. In the genus Sarda the spleen is much separated from the hver. 



EESPIRATORY SYSTEM. 



In the so-called scombroid fishes the giU-openings are very wide, extending 

 from the origin of the chin h) the posterior ventral margui of the cranium, 

 and the branchiostegal membranes not being imited at the anterior end, remain 



