GERRES. 29 



The only striking difference between the two species 

 seems to exist in the number of scales in the lateral 

 line , Günther stating that number for G. nigri at 42 , 

 whereas there are 46 in G. octactis\ but in three spe- 

 cimens of G. nigri from Liberia I find the number of scales 

 in the lateral line varying from 44 to 46. The above inves- 

 stigation may suffice to show that G. nigri and G. octactis 

 surely should be considered as quite identical. 



Now I may be allowed to point out the difference be- 

 tween G. nigri ( — octactis Blkr.) and G. melanopterus , as 

 both species differ from each other by so striking cha- 

 racteristics , that they can be distinguished at first sight. 



The upper profile of the head in G. melanopterus descends 

 anteriorly over the snout in a straight line, whereas in 

 G. nigri the profile of the snout and of the upper 

 part of the head meet at an obtuse angle just in front of 

 the eye ; in the figures given by Bleeker this difference 

 is quite conspicuous. The distance between the eyes in 

 G. nigri is about equal to the diameter of the eye , while 

 in G. melanopterus it is much smaller and contained 1'/, 

 times in the eye-diameter. The most striking difference however 

 we find in the form of the groove for the processes of the 

 intermaxillary bones. As Günther very exactly describes , 

 in G. nigri that groove is triangular , with a somewhat 

 rounded posterior angle , and widening anteriorly , so that 

 the basis measures about '/s of the distance between the 

 eyes. Yet in G. melanopterus the groove is elongate , oval, 

 with the narrower end directed forwards and the greatest 

 breadth reaching only '/. of the distance between the eyes. 

 In G. nigri the angle of the praeoperculum is round, 

 without a trace of denticulations ; in G. melanopterus the 

 (lenticulations are quite conspicuous, as was already observed 

 by Steindachner. The fact that Bleeker has not noticed 

 this in his description , must surely be imputed to the small- 

 ness of the specimen which he examined ; it only had a length 

 of 75 m.m. (without caudal), while the largest of our spe- 

 cimens measures 110 m.m. In G. melanopterus the height 



Notes Irom the Leyden Museuin, Vol. V. 



