534 EEPORT 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 

 various times and at different places about Lake Erie, something over 91 

 per cent mig-ht be called scale carp, and I should judge 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, thej are graduall}" returning to the primitive scaled condi- 

 tion, and although there are no data to show the rate at which this 

 process ma}^ have been progressing since they have become established 

 in our waters, a few ^^ears more ma}" see an even smaller proportion 

 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 crucian 

 carp {Carasskis vidgaris), 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 A'olkiriL It 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 Cyjyrinus carpio so closely tliat 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 cai'p with male crxician carp, and (2) female crucian 

 carp with male common carp, in small tanks, constructed with this end in view; (3) 

 I also put together female Carpio Icollarii with male common carp; this for the sole 

 purpose of testing the caisability of jsropagation of the C. loUarii, which had been 

 doubted. In the two former cases I obtained forms analogous to the Carpio kollurii 

 sometimes approaching in appearance the true carp, at others the crucian carp. In 

 the third case, however, having placed ripe Carpio koUarii 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 b\" pond owners, who 

 suppose that thej^ 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 {Carasslus auratus), tench 

 {Tinea tinea), and some others. The first of these is alread}^ abundant 

 in some of our waters, though the others have not as yet, at any rate, 



