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HARDWICKE'S SC IENCE-GOSSIP. 



Baird gives " very dark greenish-olive, with darker 

 margins.") Certainly we have not given the de- 

 scription of an ugly fish ; but while these colours 

 now obtain in the specimens in my aquarium, it is 

 not proper to give the impression that such is the 

 actual colouring throughout the year. Before sum- 

 mer has passed by, these more brilliant tints will be 

 materially dimmed; still it is true that if kept in 

 clear cold water, in which they will thrive, they 

 preserve to a greater degree the colours that now 

 characterize them than when in muddy waters ; and 

 here also is, I judge, the reason why the specimens 

 I have seen invariably differ from the description 

 given by Prof. Baird. His specimens were taken 

 from Cedar Swamp Creek, Cape May Co., New 

 Jersey ; and the difference, which is very marked, in 

 the water of that stream as compared with Cross- 

 weelssen Creek and its tributaries, fully explains the 

 variation in colour of the specimens from the two 

 localities. 



My aquarium specimens are now in their nuptial 

 dress. The bright tints are those that sexual selec- 

 tion has gradually developed ; and as I watch the 

 two males chasing each other to and fro, and 

 "showing off" before the passive female, I think I 

 can see the value of colour in the vexed question of 

 a species origin. 



Except when the coming duties of the care of 

 offspring force them from their retreats, the Mud 

 Sunfish is dull and uninteresting. Although quite 

 capable of executing graceful manoeuvres, and of 

 excellent swimming powers, it still seems most to 

 delight in maintaining a perpendicular position, 

 with its tail up, half hidden in the river-weed, and 

 without any perceptible motion. I have noticed 

 one of my specimens re twining this head-down and 

 tail-up position, for forty minutes ; and then, when 

 driven from his bunch of weed, he swam about very 

 listlessly, and resumed it as soon as I would let him. 

 This same position is also a favourite one with the 

 mud minnows, as we shall see when treating of that 

 fish. 



Occasionally I have gone to the aquarium to 

 watch the fishes for a while, and lo ! every tint was 

 different from that last seen. Several times the two 

 males (as I believe them to be), instead of being 

 chestnut-brown and black, were dull yellow, with 

 pale brown bands. On forcing them to swim about 

 for several minutes, I could bring back their colour ; 

 but it proved to be with them, as sometimes with 

 children, when a good lively romp brings the colour 

 to their checks ; it soon faded away, and the pale 

 tints only showed. The day following the deeper 

 colouring usually had returned. 



One word with reference to the vocal powers of 

 this species, and we will consider the Mud Minnow 

 with reference to its habits and colour. I have 

 several times noticed, but with no surprise, that the 

 supposed male sunfish I have described uttered 



prolonged grunting or "whirring" sounds when 

 chasing each other. This noise is not made when 

 they are at rest, as near as I can tell, but while in 

 rapid motion ; and, if I am not deceived, the noise 

 is accompanied by a forcing out and sudden collapse 

 of the gill-covers, followed by a stream of minute 

 bubbles of air. I have been usually baffled in my 

 attempts to see the movements clearly, both from 

 the rapidity of the motion, and the fact that the 

 sounds are only made at the close of day, when the 

 light is comparatively dim. The male chubs (Lemo- 

 tilus rhotheus) during the spawning season utter 

 similar sounds, and also the white catfish (Amiurus 

 albidus). As I have many notes bearing on this 

 subject, I propose to use them in a separate article, 

 and return to the proper subjects of this. 



The well-known and very abundant Mud Minnow 

 {Helanura limi) presents us with a second marked 

 instance of the changeableness of the colours that 

 ordinarily characterize the fish. In the aquarium 

 I have five healthy specimens, and they have never 

 exhibited uniform colouring. The female that I 

 have figured, having the abdomen nearly black and 

 the back pale brown, is in what may be called the 

 normal colouring. The others vary in different 

 degrees from this coloration, the extreme being a 

 small specimen, with the whole body below the 

 lateral line silvery white, and above the line pale 

 greyish-green, the deepest tints the most faded, 

 and there is no trace of any colour in the fins. This 

 specimen is, undoubtedly, in full health, if one can 

 judge from its movements and general vivacity, and 

 has varied less from this colouring than have the 

 other specimens from theirs. 



This variation in the colour of these fishes — and 

 it is not confined to these two species by any means 

 — is, I am satisfied, under the control of the fishes 

 to the extent cf deepening and paling the darker 

 colours. I have noticed particularly that the two 

 male sunfish, when chasing each other about the 

 aquarium, will frequently open their gill-covers to 

 their widest extent, and puff themselves out, as it 

 were, by drawing in a full breath, and then rush 

 at their antagonist. With this gill movement the 

 colours invariably deepen, growing dim again as 

 the fish draws back for a second attack. It is at 

 such time, occasionally, that one may hear the 

 whirring sound I have mentioned. 



Like the Mud Sunfish, this minnow loves to rest 

 quietly in bunches of river-weed, and whether head 

 up or down, seems to make no difference. Occa- 

 sionally the larger bunch of this weed in the aqua- 

 rium will have one of the sunfish and two or more 

 of the minnows in its branches, giving the group 

 the appearance of a tree with birds resting on its 

 boughs. 



There are several interesting points connected 

 with the life history of this minnow, which I cannot 

 now dwell upon, but will conclude with a brief 



