534 REPORT OF THE COMMISSIONER OF FISHERIES. 
destitute of scales, and those which are nearly bare are few compared 
with those entirely scaled. Of nearly 3,000 fish counted at random at 
‘arious times and at different places about Lake Erie, something over 91 
per cent might be called scale carp, and I should nue that at Lake St. 
Clair the percentage was even higher. It is very probable that under 
the present free conditions of life of these fish, with the constant inter- 
breeding, they are gradually returning to the primitive scaled condi- 
tion, and although there are no data to show the rate at which this 
process may have been progressing since they have become established 
in our waters, a few years more may see an even smaller propertion 
of mirror carp than there is at present. 
HYBRIDIZATION. 
Not only does the interbreeding of the different varieties of carp 
(using the word ‘‘ variety” in its broad sense) cause confusion, but all 
these varieties cross readily with certain closely related species of 
fishes, giving rise to a number of hybrid forms. ‘The commonest of 
these is a cross between the ordinary carp and the so-called erucian 
carp (Carassius vulgaris), a common fish in Europe. The resulting 
hybrid was described as a distinct species before its true nature was 
known, and was given the name Carpio kollarii. Jt is often known 
in Germany as the ‘‘ poor man’s carp.” In general it is intermediate 
in character between its two immediate ancestors, but often resem- 
bles Cyprinus carpio so closely that it can be distinguished only with 
difficulty. Hessel (1881, p. 868) made the following experiments in 
crossing in order to settle the question of what resulted from the 
various crosses. He says: 
In order to determine this question, I myself managed to bring about such crosses 
by placing (1) female common carp with male crucian carp, and (2) female crucian 
carp with male common carp, in small tanks, constructed with this end in view; (3) 
T also put together female Carpio kollarii with male common carp; this for the sole 
purpose of testing the capability of propagation of the C. kollarii, which had been 
doubted. In the two former cases I obtained forms analogous to the Carpio kollarii 
sometimes approaching in appearance the true carp, at others the crucian carp. In 
the third case, however, having placed ripe Carpio kollarii together with Cyprinus 
carpio, I obtained a product with difficulty to be distinguished from the genuine 
carp. I took the trouble to feed them for three years, in order to try their fitness 
for the table, but their flesh was exceedingly poor and very bony and could not be 
compared by any means to that of the common carp. 
Hessel remarks upon the frequency of this cross throughout Europe, 
and says that in many instances it is cultivated by pond owners, who 
suppose that they have the true carp. So far as I am aware the cru- 
cian carp has not been introduced into this country. But the carp is 
also said to cross readily with the gold-fish (Carassius auratus), tench 
(Tinca tinca), and-some others. The first of these is already abundant 
in some of our waters, though the others have not as yet, at any rate, 
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