78 THE SEA-TROUT 



one — an extreme case of spinal curvature — where the fish weighed 

 about 3 lb. It is often thought by anglers who catch these fish that 

 some early injury may have been the cause of the deformity, but 

 apparently the origin goes back to the unhatched embryo. Dr. 

 Gemmill's view seems to be that the actual causation has not yet been 

 definitely ascertained. 



But the most curious " monsters " found in the hatching boxes are 

 those of the Siamese Twin type (Fig. 29), where the " twins " may be 

 attached to each other in a variety of ways, the result being double- 

 headed fish, double-tailed fish, or even double-bodied fish, in which 

 extreme case the umbilical sac forms the connecting link. But of this 

 type of " monster " it is safe to say hardly any survives the alevin 

 stage. The late Mr. Cholmondeley-Pennell, however, in " The 

 Angler-Naturalist," states that, " In the river Towey, Carmarthenshire, 

 a fine fish of the Salmon or Trout species was caught, with the net, 

 which had two heads and two tails — the heads being joined on to one 

 neck, and the tails meeting about the centre. The fish was preserved 

 for some time in a small pool at Llangattock, for the inspection of 

 visitors." But the facts thus given concerning this fish are vague 

 enough. The author merely paraphrases those stated by Yarrell, who 

 adduces some evidence, with the date 1829. 



It is often asked, as a matter of interest, what proportion of eggs 

 deposited reach the fry stage; and sometimes the question is put thus, 

 how many eggs are required to produce one mature sea-trout? Con- 

 servators of fisheries would be only too glad to discover the answer. 

 Taking one year with another the proportion is doubtless fairly constant 

 and in the chapter on "Artificial Propagation " which follows I give 

 Mr. J. J. Armistead's estimate regarding trout. But unfortunately 

 there are no means of making even the roughest computation, and 

 hatchery work throws but little light on nature's operations in this 

 matter. 



