6 MEMOIES OF THE QUEENSLAND MUSEUM. 



immaturity, and as such unreliable. In the large series which has passed' 

 through my hands specimens have in rare instances occurred in which the teeth 

 of the lower preopercular limb were directed absolutely downwards ; neither this 

 character nor that of the omission of one of the dorsal rays can, therefore, be 

 taken as a valid reason for separating L. similis from Giinther's well known 

 species." 



As regards the length of the snout this is, in Mr. Stead's selected 

 specimen of P. fluviatilis, measuring 145 mm., one fourth less than the eye 

 diameter, and even in the 275 mm. example forwarded by the New South Wales 

 Fisheries Department, the two are of equal length, while in the former the pre- 

 opercular dentition is everywhere exceptionally strong, and in the latter there are 

 but nine soft dorsal rays, so that in these two picked specimens all the characters 

 of L. similis are present. It is worth noting that in Castelnau's five descriptions 

 of Lates not once does he mention the shape of the head; it is, therefore, 

 presumable that he attached no weight to this character. 



Of Lates antarcticus Castelnau I wrote : — 



' ' It is unnecessary to go at any length into the question of the validity of 

 L. antarcticus, since, with two exceptions, a comparison of Castelnau's description 

 with that given above, will show that no characters are put forward, which are 

 not equally common to P. colonorum. These are the increased number of 

 branchiostegal rays, which is stated to be seven in this species as against six, 

 which the examination of numerous specimens has shown to be the normal number 

 in P. colonorum as here and elsewhere stated, and also recorded by Prof. McCoy. 

 I do not, however, attach any importance to this seeming discrepancy, since it is 

 possible that the number is merely copied from the generic description of Lates 

 given by Giinther and which is correct of that genus,- as restricted to the two 

 species L. niloticus and L. calcarifer. It may be further pointed out that in few, 

 if any, of his descriptions of new genera and species does Castelnau take notice 

 of this important character. The second exception, namely the coloration, is not 

 of sufficient importance to justify the retention of L. antarcticus as a distinct 

 form, and this name also must, therefore, sink into a synonym of the typical 

 species. Further on (sec p. 7) I shall have occasion to refer to a form which, 

 by a casual observer, would be set down as distinct, but which, scientifically 

 examined, is easily seen to be no more than a local variety of the common 

 Australian Perch due to the greatly changed conditions under which it exists. 

 This form may possibly be the L. antarcticus of Castelnau, though, if so, it is 

 difficult to say why he should especially designate it the ' Sea Perch. ' 



"Of L. Victoria it is needless to say more than that no rational person is 

 likely to believe that the substitution of a four pointed for a single pointed spine 

 on the opercle is of itself sufficient to constitute a species. 



"In Castelnau's last form L. curtus it is only necessary to point out that 

 no reliance can be placed on the depth of the type specimen as indicative of even 



" Brit. Mus. Catal. Fish., i, 1859, p. 67. 



