DR DAVY ON THE SALMONIDA. 253 
So far as the weight of authority is concerned amongst naturalists who have 
given their attention to the subject, I believe it is in favour of the negative ; and 
on the ground, first, that the parr, according to their experience, has never been 
found in a river inaccessible by the salmon or sea-trout; and, secondly, that no 
reliance apart from this is to be placed in slight difference of form, or of colour 
or spots, as these vary in the known fry of the salmon, according to the quality 
of the water, food, and other infiuential circumstances, and in themselves, there- 
fore, are insufficient to constitute a species. 
The few who are opposed to this view, and who maintain that there is a parr, a 
distinct species, state that though rare, yet such a fish is to be met with in streams 
where the salmon and sea-trout have never been seen, and in some in which they 
assert it is impossible that either could resort, inasmuch as the access to them is 
prevented by impassable falls. Two rivers I have heard named as coming under this 
category, in which it is said that parr have been caught above falls that no salmon 
or white trout could by any possibility surmount,—one a tributary of the Shin, in 
Sutherlandshire, the other the Kirkiag, in the same county, on its west coast. 
Granting the fact that in each of these rivers there is an impassable fall, is 
the inference drawn by the advocates of the distinct species quite conclusive? 
May not the parts of the river above or below the fall have some communication 
by a channel through which a salmon or sea-trout might be able to pass, either 
subterraneous, or by some collateral branch formed during a period of flood? 
or, if nothing of the kind be discoverable on careful examination, may not the 
parr found in the upper stream derive their origin from impregnated ova of 
the salmon or sea-trout conveyed by birds, such as the water-ouzel, adhering to 
its feet or plumage, or loose in its bill? Thus conveyed, it is presumed they 
would retain their vitality, and in due time be hatched. There is a well-authen- 
ticated instance of impregnated ova of the salmon, taken even from the stomach 
of the common trout, having produced salmon-fry. 
But waving these arguments pro and con, what is the evidence that all parties 
would probably hold to be satisfactory or conclusive? Is it not the showing that 
the parr, the asserted distinct species, propagates its kind, and that in due sea- 
son, and at the same time, the male and female fish are to be found with roe and 
milt mature,—the one of its maximum size, loose in the cavity of the abdomen, 
fit for exclusion,—the other in its liquid milky state, ready for expulsion ? 
So far as I can learn, such a coincidence has never been observed. I have 
examined hundreds of parrs, and a large number from a river where the salmon is 
rare, and is never known to be taken but by the poacher in the fall of the year, 
after a flood. Male parrs I have frequently found with mature milt, but never a 
female with roe correspondently developed; on the contrary, in the female fish, 
without exception, the ovaries have been so small, that had they not been sought 
VOL. XXI. PART II. 3 Y 
