130 DUBLIN NATTJEAL HISTOET SOCIETY. 



tirely made up of fresh- water alges* and in this case the foundation is a most 

 beautiful object, being as circular as though marked out with a pair of com- 

 passes. I have also seen it composed almost entirely of decayed leaves of trees ; 

 this was in a muddy ditch, and the nest was a most untidy-looking affair. 

 Whatever materials he uses he always takes care to preserve the hole in the 

 centre, boring at it every now and then with his snout for five minutes at a time. 

 It is most interesting to watch the little architect at his labours ; one while with 

 a straw or piece of stick in his mouth, three or four times as long as himself, or 

 else carrying a bunch of confervas, in which his head is nearly completel v con- 

 cealed ; at another while either hovering over the nest, or boring at it with his 

 snout, or else attacking some audacious intruder who has dared to trespass on 

 his demesne ; for I believe it is well known that these fishes always select a spot 

 for themselves, over which they keep guard with the greatest jealousy. One 

 morning I was much entertained by a contest of this kind. Two fish had selected 

 a large flag of about two feet square as the foundation for their nests. Every 

 minute or two, either in procuring straws or in returning with them, they would 

 come in contact, then there would be a rush at each other, and in a minute or 

 two, the weaker fish having given way, there would be a chase for two or three 

 minutes, during all which time the fishes never dropped the straws, the con- 

 queror invariably returning in triumph, and sailing, proudly, two or three times 

 round his nest. They seem to have some judgment in the selection of their ma- 

 terials, as I have often observed a fish, after carrying a straw for some distance, 

 to drop it, as though of no use ; and it invariably happened that if another fish 

 took up, by any chance, a straw which had been thus rejected, he also, after a 

 short while, dropped it, as if his instinct informed him that it was worthless. 

 The time the nest takes in building varies considerably; one that I timed took 

 five hours in the building, from the time that the first layer of straws was laid 

 till the fish stopped work. I never was fortunate enough to see the operation of 

 depositing the spawn, as I never was able to spend mere than five or six hours 

 at a time watching the fish, and believe the spawn is deposited in the dusk of 

 the evening. The spawn having been deposited, the male, or, as the country 

 people call him, "fAe coc/i," mounts guard, never going far from the nest, at 

 least for a time, and may be seen hovering over the sacred deposit, ready to give 

 battle to any enemy approaching its neighbourhood. At this time they are very 

 bold and pugnacious ; and I have known them even to dart at my hand, and 

 strike me with their spines when I went to take the nest. How long this watch 

 is kept up, I am not positive, but I think it must be continued till their young are 

 hatched, as I never found a nest unguarded. These are the principal observa- 

 tions I have been able to make on this little fish. I doubt not that they have oc- 

 curred to other naturalists, but, as I do not find them recorded, I feel myself 

 justified in bringing them before your Society. 



As to the distribution of this little fish, it is found through the entire course 

 of the river, from its head, in the Butt of Kippure, to the Liffey mouth, and in 

 all its tributaries. Of other fishes, there are twelve, three of which, at least, if 

 not five, were introduced. They are: — 



1. The trout (Salmo fario), found throughout the entire length of this 

 river and its tributaries. In the upper part of the stream, near its source, they 

 run very small, seldom, if ever, exceeding from a quarter to half a pound in 

 weight. In the lower part of the stream they have been caught, weighing as 

 much as 10 lbs. The general weight, however, here, seldom exceeds 3 lbs. The 

 year before last I saw one taken on an eel-line, which wanted but an ounce of 

 4 lbs. 



2. The salmon (Salmo salar) principally come up the river during the win- 

 ter and spring floods ; salmon-fry are, however, taken nearly every autumn. 



3. The gravelling (Salmo salmulus), principally found in the lower part of 

 the stream, and swarms in the river at particular seasons. 



4. The loach (Cobitis barbatula"), found plentifully all through the river. 

 The largest I have seen was taken a liitie below the fair- green at Donnybrook ; 

 hey exceeded 6 inches in length. 



