SOME AUSTRALIAN FISH-SCALES.— COCKEBELL. 53 



Tylosurus schismatorhynchus Bleeker. Moreton Bay. The scales sent are 

 small, about 2 mm. diameter, transversely elongate, nuclens apicad of middle; apical 

 field without circuU, but with an imperfect labryinthine pattern of minute pustuliform 

 dots and lines, and frequently with very large cracks. Circuli fine, without any cross- 

 lines forming a network. 



The following key separates the Australian species of Tylosurus from the 

 Atlantic ones, so far as my material goes : — 



Circuli complete around the nucleus . . . . . . T. aciis (Woods Hole) and T. scapularis 



(Balboa, Panama Canal Zone). 

 Circuli interrupted above the nvicleus, the apical field free from circuli . . T. impotens and 



T. schismatorhynchus. 



T. acus is the tj^e of Tylosurus, if T. cantrainii is that species, as has been 

 supposed. The genus should possibly be subdivided. 



SPHYR^NID^. 



Sphyrsena obtusata Cuv. & Val. Moreton Bay. The larger scales are about 6 

 mm. long and 8 broad ; smaller ones are about square, and probably come from near 

 the tail. There is an exceedingly fine and dense system of circuli and radii, the basal 

 circuh finely beaded, or rather crenulate. In the apical field the radii are lost, but 

 the circvili continue, but become broken up in the submarginal area into irregular 

 labyrinthiform markings. The basal radii are only about 112 microns apart. 



This may be compared with S. picuda B. & S., from Tampa, Florida, which has 

 the same dense radii and circuli, but the circular fibrillse are considerably coarser and 

 less distinctly crenulate. In both these species the radii are continuous, at least in 

 the basal field, not moniliform or reduced to a series of pit-Hke structures as they are in 

 S. borealis De Kay from Woods Hole. Thus the large-scaled species seem readily 

 separable on the structure of the scales from the smaller-scaled forms such as *S^. borealis. 

 The type of the genus has even smaller scales than S. borealis. 



HOLOCENTRID.E. 



Holocentrus ruber Forsk. Barrier Reef. Scales about 7 mm. long and 10 

 broad, the apical margin irregularly dentate ; apical field pitted ; five or six basal 

 plicae, close together, making the middle of the basal margin deeply undulate ; circuli 

 very fine and numerous ; microscopical cracks forming lines as in Tylosurus acus. 

 This is scarcely difi^erent from other Holocentrus scales. H. microstoma from Samoa 

 has the marginal teeth much longer, sharper and closer, and the basal plicae weaker 

 and less regular. H. laticeps from Kaui has the teeth like those of H. microstoma, 

 but the plicae (only three or four) hke those of H. ruber. H. xantheryilirus from Hawaii 

 has teeth of the same general type as H. ruber. H. diadema from Hawaii is like 

 H. laticeps. 



Thus, according to the scales, H. ruber and xantherythrus might be grouped 

 together, apart from the other species mentioned. 



TOXOTIDiE. 



Toxotes chatareus Ham. Buch. Norman River. Scales 6 to 8 mm. long and 

 broad, subquadrate, but with rounded comers ; circuli very fine, the lateral ones 



