350 PKISTIPOMATIDiE. 



scales of the ujjper surface of the skull do not extend over that 

 groove, forming a stripe between the groove and the orbit, and ter- 

 minating a little behind the nostrils, which are situated high up the 

 sides, close to the orbit, and remote from the end of the snout. The 

 pra3orbital is entirely scalcless, and without any denticulations ; 

 anteriorly broad, it is narrowest between the maxillary and the 

 orbit ; its maxillary margin is semilimate. The scales of the cheeks 

 are rather smaller than those of the body, and extend on that part 

 of the mandibula which is situated immediately behind the maxil- 

 lary ; they are arranged in fom- series on the prseoperculum and in 

 two on the mandibula. The angle and the inferior margin of the 

 prseoperculum form one curve : a narrow space along this curve is 

 scaleless ; it is about as wide as one of the scales of the cheek. The 

 operculum is irregularly quadrangular, with the posterior side slightly 

 emarginate ; the inferior is straight, obliquely ascending backwards. 

 The sub- and intoroperculum are covered with deciduous scales, like 

 the operculum ; their inferior margins form one convexitj'. 



The dorsal fin is not very deeply notched ; the length of the base 

 of the spinous portion is two-thirds of that of the soft, and the 

 distance of the dorsal from the caudal is not quite one-third of that 

 from the end of the snout ; its origin is a little behind the vertical 

 from the base of the ventrals, whilst the extremities of the dorsal 

 and anal fins correspond to each other. The spines are rather slender : 

 the first is very short ; the second the liighest and somewhat flexible, 

 its length being If in that of the head, and 24- in the height of the 

 body ; the third is rather shorter ; and the follo-\\'ing gradually de- 

 crease in length to the last, which is one-half of the second. The 

 first ray nearly equals the sixth spine. The caiulal fin is entirely 

 and densely covered with minute scales, and deeply forked, the 

 middle and si artest ray being one-fifth only of the outer and longest 

 rays ; the upper lobe is rather longer than the lower, and nearly 3^ 

 in the total length. The origin of the anal fin falls beneath the fifth 

 ray of the dorsal, whilst the extremities of both fins correspond to 

 each other ; the length of its base is rather more than its distance 

 from the caudal, and rather less than the distance between the ante- 

 rior margin of the eye and the hinder end of the operculum ; it moves, 

 like the dorsal, in a deep scaly sheath. The first spine is very short ; 

 the second strong, its length being If in that of the head, and 3| in the 

 height of the body ; the third is rather shorter, and half as stout as 

 the second. The fii'st ray has about the length of the second spine, 

 whilst the following rays diminish in length, so as to form a concave 

 margin of the fin. 



The pectoral fin is rather elongate, the middle rays being the 

 longest ; it reaches nearly to the origin of the anal fin, and is 3| in 

 the total length. The base of the ventral fin falls behind that of the 

 pectoral ; it is partly covered with stripes of minute scales ; it does 

 not reach to the vent, and is 6 g in the total length ; it is composed 

 of one spine, slightly curved, and three-fourths of the adjacent ray, 

 and of five rays, the last of which, as in all the species of Gerres, is 

 split into two branches to its base. 



