M. P. Gervais on the Freshwater Fishes of Algeria. 131 



which acts as a "He-beam^* to a portion of the arch, and without 

 much expenditure of force supports the weight of the body 

 placed on the vertex of the straddhng arch formed by the tail 

 and hind feet. 



I do not know of any other animal in which the quadratus 

 femoris is inserted so low down on the femur, nor of any in 

 which, as in the kangaroo, a special trochanter is provided for 

 the insertion of this muscle. Its weight is 



In the Giant Kangaroo \'47 oz. 



In the Wallaby 0-91 „ 



The relative moment of the quadratus femoris in man,' the 

 Quadrumana, and the kangaroos may be seen from the following 

 comparison : in all cases the total weights of the hip-joint 

 muscles being called 100, the quadratus femoris forms of the 

 hip-joint muscles 



In Man 1 -25 per cent. 



In the Chaema 3*01 „ 



„ Green Monkey 3*00 „ 



„ Macaque 4*01 „ 



„ Wallaby Kangaroo 5*06 „ 



„ Giant Kangaroo 3*77 „ 



XXIV. — On the Freshwater Fishes of Algeria. 

 By Paul Gervais*. 



In a memoir published as long ago as the year 1853 f, I gave 

 some descriptive details of the fishes which had then been col- 

 lected in Algeria in the different streams and in some lakes of 

 that country, and showed how little they varied specifically. 

 Including Coptodus and Tellia, both differing generically from 

 European fishes, the number amounted only to seven, namely, 

 Coptodus Zilliij a species of Tilapia ; Zillia apoda, of the family 

 of Ci/prinodontes ; a Bleak [Leuciscus callensis, Guichenot); three 

 Barbels, one of which even is contestable {Barbus callensis, Val., 

 B. setivimensis, Val., and B. longiceps ?, Val.) ; lastly, an Eel, to 

 which M. Guichenot also thought it necessary to give a specific 

 name [Anguilla callensis). This list has since been increased 

 only by two interesting species, a Trout (Salar macrostigma, A. 

 Dum^ril J) and a Cyprinodon (C. duliatus and cganogaster, 



* Translated by W. S. Dallas, F.L.S., &c.,from the * Comptes Rendus,* 

 I7th December 1866, pp. 1051-1058. 



t Bull. Soc. d'Agric de I'Herault, xl. p. 7G; Ann. des Sci. Nat. 3« 

 serie, xix. 



X Revue et Magasin de Zoologie, 1858, p. 396, pi. 10. 



