386 PROCEEDINGS OF SECTION D. 



This in either genus consists in its most typical expression of 

 thi-ee transverse cross-bands, the third or hindermost of 

 which, at the base of the caudal fin, is commonly represented 

 by a single spot. In the freshwater genus Barhus all 

 three of the cross-bands may be represented by as many spots, 

 while in both genera it commonly happens that the central 

 and anterior cross- bands have entirely disappeared and a 

 single tail-spot alone is left. This single tail-spot, the 

 remnant of an original posterior transverse bar, recurs in a 

 large and heterogeneous series of fish types. The single dark 

 spot situated immediately behind the operculum or at the 

 base of the pectoral fin in a correspondingly large number of 

 species apparently represents in an equivalent manner the 

 surviving trace of a pre-existing anterior bar. 



One of the most singular modifications of the three-barred 

 pattern ]-eferred to in association with the two genera Ayogon 

 and Barilius is met with in the Indo-Austrahan pereoid 

 type Gengoroge sehce. In this fish the anterior and posterior 

 bars converge superiorly towards the central one in such a 

 manner as to produce in combination with it the contour of 

 a conventional broad arrow ; and the fish is hence known to 

 anglers in ports of Queensland, where it is plentiful, by the 

 suggestive popular title of the "Government Bream." 



Examples of fish in which the normal series of transverse 

 bars are separately divided up into a number of smaller spots, 

 thus paving the way to the irregularly or profusely spotted 

 types, are illustrated notably, among many others, by various 

 species of the two Australian genera Gerres and Pristipoma. 



The list already quoted might be indefinitely lengthened. 

 A sufficiently long one, however, has been now brought 

 forward to meet the object of this paper, and which is to 

 direct attention to the evident orderly warp that lies beneath 

 the complex and otherwise altogether incomprehensible over- 

 lapping weft of the colour markings of fish. To those who 

 have the leisure and opportunities for picking u]) the threads 

 of the somewhat tangled elements brought forward on this 

 occasion, the subject may be commended as one well worthy 

 of attention, and as calculated to bring to light data of high 

 interest concerning the common ancestral or phylogenetic 

 relationship of many fish that have been hitherto regarded as 

 most remotely separated members of the same zoological 

 class. 



