520 CENTEISCID-E, 



and nostrils is scaly. The interoperciilum is extremely narrow and 

 elongate. Operculum higher than long, obtusely rounded ; suboper- 

 culum subcrescentic. Four slender branchiostegals. The gill-opening 

 extends to below the eye, the gUl-membranes being attached to the 

 urohyal : the giossohyal is long, feeble, gradually lost in the mem- 

 brane which forms the bottom of the rostral tube. Four gills, Avith 

 a narrow slit behind the fourth ; pseudobranchiae well developed. 



The body is strongly compressed and more or less elevated ; its 

 greatest depth is between the ventral and dorsal fins, where it is 

 contained once and three-fourths to twice and one-third in the 

 distance of the operculum from the caudal fin. Its upper profile 

 gradually ascends towards the spinous dorsal, is nearly horizontal 

 between the origins of the two dorsal fins, descending abruptly along 

 the base of the second dorsal, and shelving towards the caudal. The 

 lower profile is a slight, regular curve. The whole body is covered 

 with small scales, which are striated, each stria terminating in a 

 comparatively strong spine. 



Several bony strips are visible on the side of the back : one arises 

 from the side of the nape and proceeds towards the first dorsal spine, 

 where it meets its fellow of the other side. Another strip com- 

 mences from the scapulary region and represents a sort of lateral 

 line ; it is composed of three bones, each bone having a horizontal 

 atid an oblique portion, which cross each other. The margins of the 

 thorax and of the abdomen are covered with several bony plates 

 which have a cutting longitudinal ridge along the middle. 



The pectoral fins have a short and oblique base, and are inserted 

 below the middle of the depth of the body : they equal in length the 

 distance of the anterior margin of the orbit from the posterior of the 

 operculum, and extend to above the middle of the ventral fins ; the 

 rays of which they are composed are simple. The ventral fins 

 stand as close together as in a Gobioid, and are received in one 

 common groove on the belly ; they are very short, apparently without 

 spine, and composed of five rays, the middle of which are spht nearly 

 to the base. 



The first dorsal fin commences in the middle of the distance be- 

 tween the occiput and the caudal fin ; it is composed of five spines, 

 the first of which is very short, moveable, the three posterior being 

 much longer than the first, though rather feeble ; they are connected 

 with the second spine by a strong membrane. The second spine is 

 exceedingly strong and long, compressed, striated, grooved poste- 

 riorly, and strongly serrated ; it cannot be erected in a vertical line, 

 but always remains obliquely pointing upwards and backwards ; its 

 length appears to vary in different individuals : — 



