ORIGIN, SYSTEMATIC POSITION 



7 



He also drew attention to the resemblance between the air-bladder of the young 

 Turbot and that of Zeus, and to the presence of small spines on the gill-covers of 

 young Turbot similar to those which occur as a juvenile character in the John Dory. 

 On closer investigation many of these features are seen to be of comparatively little 

 importance, and comparison of the internal anatomy, and more particularly of the 

 osteology, of Psettodes with that of Zeus produces very little evidence to support the 

 view that these fishes are in any way closely related.' The peculiar characters of 

 the order Zeomorphi as defined by Regan (igioA) are, almost without exception, absent 

 in Psettodes. These include the more or less separate spinous anal fin ; the caudal fin 

 with only 12 or 13 principal rays, of which 10 to 12 are branched, and, in addition, 

 I to 3 small, simple rays above and below ; the simple post-temporal, which bridges 

 the posterior temporal fossa, is rigidly united to the epiotic or parietal above and to the 

 opisthotic or pterotic below, and has a " temporal plate " firmly attached along its 

 anterior edge ; the cleithrum, which runs upwards internal to the supra-cleithrum 



. 7. — Jaws and palatine b 

 articular; d.,dentary; mx. 

 mental maxillary. (X J.) 



. Psettodes er 

 ■ i pn/.,palatii 



:, F.pmcplidu 

 ., pra?maxilla: 



and ends in a pointed projection just behind the post-temporal ; the single post- 

 cleithrum on each side ; the first vertebra, which is very firmly attached to the 

 cranium ; the praecaudal region of the vertebral column, in which the anterior neural 

 spines are directed backwards, but the posterior spines are erect or even point forwards 

 (Fig. 6). In the Zeomorphi, moreover, each pelvic fin is composed of a spine and of 

 from 5 to 9 branched rays, a character suggesting affinities with the Berycomorphi. 



Finally, on comparing Psettodes with a generalised Percoid (Figs, 2, 3, 4), the 

 resemblances are so striking that there can be very little doubt as to its relationship 

 with these fishes ; indeed, apart from the asymmetry and the long dorsal and anal 

 fins, Psettodes might almost be placed in the Percoid family Serranidse. The most 

 important features of resemblance include the form of the dorsal fin, which in Psettodes 

 has about the first 10 rays composed of slender spines and does not extend fonvard 

 on to the head ; the caudal fin, which has 17 principal rays, of which 15 are branched ; 

 the pelvic fins, each of which consists of a spine and 5 soft rays. The maxillary is 

 provided with a well -developed supplemental maxillary, and the form of the mouth is 

 that of a typical perch. Apart from its asymmetry, the skull is in most respects 



' See Regan (1910B, p. 486). 



