1. FISTiri-AKIA, 531 



interopcrciilura is exceedingly long and narrow, hidden below the 

 prteoperculiim and tympcanic. The gUl-opening is wide, closed above 

 the operculum ; the gUl- membranes are only slightly united at the 

 base of the ui'ohyal. Fixe slender branchiostegals : the first (nearest 

 to the subopercle) is divided into two branches, so that one might 

 •easily take it for two branchiostegals ; they are, however, united at 

 the base. Four gills, with a wide slit behind the fourth ; pseudo- 

 branchite well-developed. The arcus branchiales have no internal 

 rakers; the lower pharyngeals are very narrow, provided with a 

 long series of viUiform teeth ; a series of three elongate patches of 

 similar teeth on each side of the roof of the pharynx. The glosso- 

 hyal is exceedingly elongate, half as long as the tube. 



The bony shields which protect the anterior portion of the trunk, 

 and are situated immediately below the skin, will be better described 

 with the skeleton. This portion of the trunk has the muscles much 

 less develojied than the posterior ; the shields are the following: — 



1. A narrow strip along the median line. 



2. A pair of broader ones occupying the sides of the back. 



3. A narrow one on the side. 



4. The pubic bones on the belly. 



The ventral fins are situated on the muscular portion of the trunk, 

 and a striji of bony, needle-Hke ossifications, imbedded in the skin, 

 runs from each fin to the pubic shield, being continued posteriorly 

 along the whole length of the side of the abdomen nearly to the 

 caudal fin. The body is much depressed, broader than liigh, and 

 gradually tapering posteriorly ; it is nalied ; the lateral line is marked 

 by pores and by small, narrow, bony shields, which are sunk in the 

 skin anteriorly, and become broader and more projecting on the taU, 

 where they form a sort of serrature. The lateral line commences in 

 the scapulary region, is cui'ved towards the median line of the back, 

 running along the whole length of the dorsal shield, and then bent 

 downwards, proceeding along the middle of the side. The vent is 

 situated immediately before the anal fin. 



The pectoral tin has an obhquely curved base and a rounded mar- 

 gin ; it is scarcely longer than the bony orbit, and all its rays are 

 simple ; there is a small furamen posteriorly in its axil. The ven- 

 tral fin is much shorter than the pectoral, and composed of six soft 

 rays, the outer being the longest, simple, and articulated towards its 

 extremity. Both fins are widely apart from each other, and their 

 distance from the pectoral is one-third of that fi'om the caudal. 

 The dorsal fin is much higher than long, and composed of simple and 

 irnarticulated compressed rays, the sixth of which is the longest ; 

 the posterior rays decrease rapidly in length ; the fin is opposite to the 

 anal, and its distance from the caudal fin is one-fourth of that from 

 the occiput. Anal fin very similar to the dorsal. The caudal fin is 

 deeply forked ; its two middle rays are produced into one exceedingly 

 long filament ; sometimes they are disconnected from each other, 

 forming two filaments ; the upper and lower rays are simply forked. 



The colour of the upper parts is reddish-brown, variegated with 

 numerous blue spots on the sides and on the back. 



2m2 



