FISHES 



although the elongated, rays in the anal (or ventral) fin are 

 the most anterior, the rays of the dorsal which are elongated 

 are not the most anterior, but are situated some distance 

 behind the commencement of the fin, and opposite to the 

 elongated rays of the ventral. This fact tends to support the 

 view that the elongation is due to some special stimulation of 

 the particular fin-rays, not to a general tendency in the most 

 anterior rays to elongation. In this case we know nothing of 

 the habits of the fish, or of the way in which it moves its 

 rays. But if there is some special stimulation which in this 

 case has acted on the thirteenth to nineteenth dorsal rays, 

 and in other cases on the anterior dorsal rays, the observed 

 condition is explained, whereas we cannot believe that selec- 

 tion from among the variations which occur in the dorsal fin 

 of other flat fishes for instance, Sole, Plaice, or Flounder- 

 could have produced such a modification. 



Elongated fin-rays occur in two other species described in 

 the same report, but do not appear to be confined to one sex. 

 One of these is Rhomboidichthys angustifrons. In the single 

 specimen obtained the anterior dorsal rays were produced, 

 and were nearly detached from the adjacent rays. The sex 

 of the specimen is not mentioned; it was obtained at 30 

 fathoms in the Arafura Sea. In Zophonectes gallus the five 

 anterior dorsal rays are prolonged in both sexes, but the 

 adult males were distinguished by another character, namely, 

 the presence of pointed tubercles on the snout, two on the 

 sides, one at the mandibular symphysis. Specimens of this 

 species were obtained' off Port Jackson in the Bass Straits, at 

 a depth of 30 fathoms. 



Sub -order Acanthopterygii. Sparidce. There are 

 many families in this Order in which no conspicuous 

 sexual differences are present. Cantharus lineatus, the 

 Black Sea -bream, requires to be considered, because its 

 behaviour during the breeding season has been observed by 



