202 Mr. J. McClelland on Indian Cyprinidae. 



species in favour of India is so remarkable, that it is only by 

 extending our consideration to other genera of the order 

 Malacopterygii abdominales, that we find the equilibrium re- 

 stored in the distribution of freshwater fishes. Thus the 

 Salmonidm, which form a large proportion of that order in the 

 rivers of both Europe and America, are in India quite un- 

 known ; not one species of that extensive family having yet 

 been found in this country, where the blank appears to be 

 filled up by the excessive development of the Cyprinidce. 



54. One species of Tench*, four Leuciscst, and one Gud- 

 geon {, are enumerated among the fossils of (Eningen by 

 M. Agassiz, who also describes two new genera §, Rhodeus 

 and Apius, nearly allied to, but distinct from, the Perilamps 

 and Systoms. They are distinct from the first by the 

 dorsal and ventral margins being equally arched, and the 

 caudal and anal fins being less developed ; and from the 

 second, by the absence of spines in either of the latter fins : 

 both belong however to Sarcoborinae, and will serve to render 

 that group far more complete than it appeared to me to be 

 before I saw M. Agassiz's splendid work. Two fossil species 

 of Cobitince are also found in the same locality ; one of these, 

 C. cephalotus, Agass., belongs to Schistura. The marlstone 

 in which these remains are found is justly considered by M. 

 Agassiz to be a lacustrine deposit, and supposed to be coeval 

 with the molasse of Switzerland and the sandstone of Fon- 

 tainbleau, and consequently to correspond with the miocene 

 or early tertiary period. 



55. That the external covering of animals indicates the 

 medium in which they live, we know by the hairy coat of the 

 Mammalia, the feathers of birds, and the scales of fishes and 

 Amphibia; nevertheless there are several families of fishes 

 without scales, and many terrestrial Mammalia that are sup- 

 plied with them instead of hair. In the naked fishes the 

 body is defended by a copious oily mucus, which saves it no 

 less effectually than scales from the abrasive influence of the 

 dense medium through which they are destined to move ; 

 while their habits and form render the necessity for a scaly 

 armour less essential to their safety, being capable of con- 

 cealing themselves from enemies in sand and mud, as the 



* Tinea leptosoma, Agass., ' Recherches sur les Poissons Fossiles/ vol. v. 

 t. 51. 



f Leuciscus papyraceus, Agass., vol. v. t. 36 ; L. leptus, Agass., vol. v. 

 t. 57 ; L. pusillus, id. 1. c; L. CEningensis, id. and L. heterurus, id. 1. c. 



% Gobio analis, Agass., t. 57. 



§ Rhodeus elongatus, Agass., t. 54, and JR. latior, id. 1. c. Of the genus 

 Apius, M. Agassiz describes A. gracilis and A. Brofigniarti, vol. v. t. 55 ; 

 but the latter, as well as Leuciscus papyraceus, are from the lignites of 

 Menat. 



