BY THE REV. J. E. TENISON-WOODS. 177 



Japanese salmonoid named Plecoglossus, which, however, is a 

 very aberrant type. 



The actual boundary of the Indian fresh-water fish region is 

 difficult to define in South China, but the tributaries of the 

 Yang-tse-kiang carry some of its species considerably north of the 

 tropical line. Much, however, of the uncertainty as to the limits 

 of genera and species, is owing to the little knowledge we possess 

 of the counti-ies through which the northern tropical line passes. 

 Any conclusions that are formed now must only be considered 

 provisional and subject to considerable modification. 



Dr. Giinther supposed that the fresh waters of Persia have 

 been converted into brine and finally dried up by geological 

 changes. Before this the streams were inhabited by many Indian 

 forms, of which a few survive between Afghanistan and Syria. 

 phioce2)hcdus and Discognathus (Carp) have one representative 

 each : Macrones (Siluroid) survives in the Tigris : Mastacemhelus 

 at Aleppo. Thus, he adds, Indian fresh-water fishes, with those 

 of Africa and Europe, mingle in a district which connects the 

 three continents. 



There are thii^ty-nine families of fresh-water fishes known, of 

 which twelve are represented in the Indian region. They number 

 625 species or two-sevenths of the known fresh-water fishes. Of 

 these about 200 are Siluroids, and over 300 Carps. The pre- 

 ponderance of these two families is the speciality of the Indian 

 region. There ai-e no known Ganoid or Cyclostomous fishes, though 

 they are present in every other region. We have, however, an 

 Osteoglossum, one of the many families of the immense order of 

 Pjiysostomi. Osteoglossimi is a remarkable-looking fish; the body 

 is covered with large hard scales, composed of pieces like 

 tesselated armour : head scaleless, the skin being entirely replaced 

 by bone : lateral line composed of wide openings of the mucous 

 duct ; dorsal tin on the tail opposite to the anal fiu and very 

 similar to it — both confluent with the rounded anal: mouth 

 oblique, wide : lower jaw prominent, with a pair of barbels : 

 pectoral fins long. The general appearance at fii\st sight reminds 

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