584 TELEOSTEI CHAP. 



travelling long distances, against rapids and over waterfalls, to 

 reach their breeding places at the heads of rivers. During the 

 breeding season, the males of many species assume a more 

 brilliant livery, or develop pearl-like or spiny excrescences on 

 various parts of the head, or also on the body and fins. 1 Cyprinids 

 are oviparous, with the exception of a small Barbel from Natal, dis- 

 covered and described by Prof. Max Weber as Barbus vivipar//*. 



A most striking instance of symbiosis is offered by a little 

 Carp -like fish of Central Europe, the " Bitterling " (Khodeus 

 amarus). The genital papilla of the female acquires a great 

 development during the breeding season, becoming produced into 

 a tube nearly as long as the fish itself; by means of this ovi- 

 positor the comparatively few and remarkably large eggs, measur- 

 ing 3 millimetres in diameter the fish being only 60 to 80 

 millimetres long are introduced through the gaping valves, 

 between the branchial laminae of pond mussels (Unio and 

 Anodonta) where, after being inseminated, they undergo their 

 development, the fry leaving their host about a month later, 

 having attained a length of 10 or 11 millimetres.' 2 The mollusc 

 reciprocates by throwing off its embryos on the parent fish, in 

 the skin of which they remain encysted for some time, the 

 period of reproduction of the fish and mussel coinciding. 



Some members of this family grow to a very large size, 4 to 

 6 feet ; such is the case with the Carp, a native of Asia, intro- 

 duced into England towards the beginning of the seventeenth 

 century ; the Catla (Catla buchanani') of India, Burma, and Siam ; 

 the Mahaseer (Barbus mosal} of the mountain streams of Asia, 

 the scales of which may be as large as the palm of a hand ; and 

 Hypophthalmichthys molitrix of China and Manchuria, remark- 

 able for the low position of the eyes, the fusion of the gill-rakers 

 into thin plates of spongious appearance, which must act as a 

 most efficient sifting apparatus, and the presence of an involuted 

 problematic superbranchial organ to each branchial arch. 3 



Among well-known aberrations produced by artificial selection 

 may be mentioned the " Leather Carp," a race in which the 

 scales are either lost or much reduced in number, and enlarged 



1 Cf. Baudelot, Ann. Sci. Nat. (5), vii. 1867, p. 339, and Leydig, "Unters. 

 Anat. u. Histo]. d. Thiere " (1885). 



2 Cf. Noll, Zool. Gart. 1869, p. 257, and 1877, p. 351 ; Olt, Zeitschr. wiss. Zool. 

 Iv. 1893, p. 543 ; Cuenot, Bull. Soc. Zool. France, 1898, p. 53. 



3 Boulenger, Ann. and May. Nat. Hist. (7), viii. 1901, p. 186. 



