296 MR. E. w. L. noLT ON THE [-A-pr. 19, 



fin from side to side. In females and undifferentiated males the 

 hind part of the fin is occupied by a dark marking which some- 

 times takes the form of an intense black spot extending over 

 nearly half the fin. It is my impression that the individuals with 

 the darkest fins are more prone to display than their paler brethren, 

 but I should not like to iusist on the correctness of this obser- 

 vation '. In table-tanks a momentary elevation of the pale second 

 dorsal is difficult to detect. I therefore made (on the 11th April) 

 some experiments in the deep aquarium tank with a view to 

 more satisfactory observation of this point. A half-grown Tub 

 Gurnard (Trigla hirunclo) and an Angel (Rhina squatin'a) were 

 successively introduced into the Dragouet tank. I was able to 

 satisfy myself that on the near approach of either of these fish 

 the young Dragonets sometimes elevated both dorsal fins. The 

 elevation of the second was always of very short duration, and in 

 some cases only partial. Some of the specimens seemed content 

 to rely entirely on their resemblance to the gravel (as I have also 

 noticed iu catching them), and did not hoist their fins at all. 

 One specimen, which made violent endeavours to leap out of the 

 tank on the approach of the gurnard, was, and remained for some 

 time, unusually pale after returning to the bottom. A similar 

 change of colour was pointed out to me by Mr. T. W. Gramble in 

 one of two young specimens taken from the table-tank on the 

 same day. The emotion of terror appeared in both cases the 

 most probable stimulus. As contrasted with the large differentiated 

 males small Dragonets certainly display their fins, in the presence 

 of danger, much less invariably. On one occasion, the intruder 

 being a turbot, it was observed that a young Dragonet, near 

 which the turbot had settled, erected the fore part of its body 

 by a vertical depression of the pelvic fins and remained in this 

 attitude until the turbot went away. The Dragouet was not on 

 the gravel, but on a white ledge of the side of the tank. The 

 attitude may possibly have been intended to enhance its apparent 

 size, or may have been merely a preliminary to flight, if attacked., 

 The dorsal fins were not erected. 



It is noteworthy that large males, when threatened, do not 

 assume the full courting attitude. The cheeks may be puffed out, 

 but the jaws are never protracted to the full extent, and sometimes 

 not at all. The preopercular tridents can be thrust out free of 

 the sides of the head at will ; but I have never seen this done in 

 the water, unless the fish were actually seized. It will then 

 strike with its head from side to side. 



' Poulton (' Colours of Animals,' p. 166) has quoted a suggestion of 

 Mr. Garstang's to the effect that the black first dorsal of theWeever {Trachimis 

 vipcra) may subserve the function of a warning signal. It has been suggested 

 by Cunningham (Journ. M. B. A., n. s. vol. i., 1889, p. 37) that the Dragonets 

 and Weavers are allied forms. Apart from the question of affinity, there is the 

 obvious suggestion of mimicry, on the part of the non-poisonous Dragonet, of 

 the really formidable Weever, but some farther investigation of the habit and 

 habitat of the two forms seems indispensable to a profitable discussion of this 

 question. 



