BARBUS. 197 



from 30 to 47 (16-26 + 14-21) according to the species. The numbers in the Nilotic 

 species examined by me are as follows : — 



B. bijnni 23 + 18-41 



B.affinis 23 + 19 = 42 



B.nedgia 23 + 19 = 42 



B. intermedins 23 + 18 = 41 



B. gorguari 23 + 19 = 42 



B. perince 18 + 16 = 34 



B.humilis 17 + 16 = 33 



In B. bynni and allies the interneurals of the enlarged dorsal rays are more 

 strongly developed and the preceding interneurals form a continuous series to the 

 occipital crest, whilst in B. perince a wide gap separates the occiput from the first 

 interneurals. 



The digestive tract is usually longer than the whole fish, either a little, as in 

 B. perince and other small species *, or very much, as in B. bynni and most of its near 

 allies, in which it measures once and two-thirds to twice the total length, and in 

 B. intermedins, in which its length, in the adult, may be as much as three or four 

 times the total length. 



The fishes of this genus have a mixed diet, either the animal or the vegetable food 

 predominating, according to the greater or less elongation of the intestine. External 

 sexual differences are not marked in any of the species with which we have to deal 

 in this work. 



As to the changes which take place with age, it should be pointed out that the 

 barbels and the rays of the anal fin are proportionally shorter, whilst the last simple 

 ray of the dorsal fin is longer, in the young than in the adult ; these changes have 

 been duly considered in drawing up the following synopsis. 



In measuring the length of the caudal peduncle, the muscular part of the tail only 

 is reckoned, whilst at least one vertical series of scales covers the base of the 

 caudal fin. 



The genus Barbus comprises some 300 species, distributed over Europe, Asia, and 

 Africa. The greater number are from South-eastern Asia; about 130 are African. 

 This multitude of forms has been divided into a number of sections, which are so 

 completely linked together as to preclude their being properly raised to generic rank. 

 The first section to be mentioned, because it includes the type of the genus, the 

 Cyprimis barbus of Linnaeus (Barbus vulgaris, Cuv.), is characterized by a dorsal fin 

 with the last simple ray bony and serrated, 5 branched rays in the anal fin, four barbels, 

 and small scales (more than 40 in the lateral line), the exposed portion of which is 



* As pointed out by Peters in 1868 (Eeise Mossamb. iv. p. 52), in some of the small Barbels, such as 

 B. paludinosus, the digestive tract may be even a little shorter than the fish, thus showing the fallacy of a 

 division into Macroenteri and Braehyenteri. 



