34 NATURAL HISTOEY OF THE SALMON. 



the temperature of the water was 40 when the 

 ova were deposited never falling below 36, and 

 by the 1st of March the eye and round form of 

 the fish could easily be detected in both kinds, by 

 the naked eye, and an ovum, when put in the 

 hollow of the hand, would turn itself round. 

 Peter Marshall, th*e keeper at the Stormontfield 

 pond, who was in the habit of examining them 

 regularly, stated that they were about a fortnight 

 earlier than the ova at that place, which had been 

 deposited at the same date. But about this time, 

 on account of a deficient supply of filtered water, 

 a quantity of unfiltered water was allowed to 

 enter the pipe; this water contained a large 

 amount of the larvae and grubs of insects, par- 

 ticularly of a small black water beetle, and by the 

 end of April all the ova were devoured. Their 

 method of procedure was as follows : the grub 

 fastened on a live ovum, and pierced a hole in 

 the shell, the colour instantly changing from a 

 salmon colour to opaque white : the egg was 

 devoured at leisure afterwards. The Messrs 

 Ashworth, proprietors of the Galway fishings, 

 experimented on the May-fly, and their report is, 

 "that the larvae of the May-fly are known to be 

 most destructive " in proof of this being the case, 



