122 Dr. Richardson's Contributions to 



tail the fish becomes gradually much compressed, the thickness of the 

 trunk of the tail not exceeding one-third of its height. 



The head is rather thick and convex above. The distance between 

 the eyes is equal to the vertical diameter of the orbit, and the snout 

 is very short. The moderately large eye is placed high up, occasion- 

 ing apparently the arching of the frontal bone : it is half a diameter 

 from the edge of the snout, a diameter and a half from the under 

 surface of the head, and two and a half from the tip of the gill-flap. 

 The nostrils are situated on the verge of the orbit, above its upper 

 anterior angle, the two orifices being contiguous, and the foremost 

 one emitting a cirrhus which is two lines high. The mouth opens 

 forwards and is of moderate extent, the jaws not separating beyond 

 an angle of 60°. The under jaw is equal in length to the upper 

 one, but as it ascends when the mouth is closed, it appears slightly 

 longer when depressed. The lips are thin. The intermaxillaries are 

 moderately protractile, and, owing to the shortness of the snout, their 

 pedicles, which are of the same length with the oral limbs of the 

 bone, slide over the anterior third of the orbit. The maxUlary is 

 wide at its lower end and evenly truncated, and its upper end is 

 only very partially covered by the edge of the preorbitar. The lips, 

 jaws, isthmus, and branchial membrane are the only parts of the 

 head that are not scaly ; the snout, top of the head, suborbitars, 

 cheeks, and whole opercular pieces being densely covered to their 

 extreme edges with scales. The preorbitar is narrow, and curves 

 away to a thin slip as it passes under the anterior third of the orbit ; 

 it is scaly, though the scales, being imbedded in integument full of 

 small pores, are not easily seen unless in the dried specimen. The 

 rest of the suborbitar chain is restricted to a smooth mucous canal 

 or fold which divides the orbit from the densely scaly cheek. Nei- 

 ther the margin of the orbit nor the preorbitar show any acute 

 points, though the anterior edge of the latter is slightly uneven. 

 There are many minute pores with branching mucous tubes on the 

 lower jaw not disposed in any regular order. 



The upper limb of the preoperculum inclines slightly forwards as 

 it ascends, and is finely and very acutely serrated ; the teeth are di- 

 vergent on the rounded angle and a little stouter ; and the under edge 

 of the bone, which is slightly arched, is occupied by three strong 

 conical and very acute spines which point forwards. The foremost 

 of the three is the largest, being twice as long as the posterior one, 

 which is less than the middle one. These spines lie beneath the 

 scaly edge of the bone, and are not readily seen in the recent fish. 

 The whole edge of the preoperculum is free to a considerable extent, 

 and can be raised from the gill-cover. The gill-flap is triangular, 

 its under edge sloping much upwards to the not very acute scaly 

 tip, which is situated high above the pectoral fin and nearer to the 

 lateral line. There is no membranous margin to the flap, and the 

 scales conceal the unions of the opercular pieces. The under edges 

 of the interoperculum and suboperculum are quite entire. A flat 

 acute spine is situated on the operculum, about its own length from 

 the tip of the gill-flap and immediately behind it. 'I'he point of a 



