CLASS PISCES. 411 



Malapterurus, Lacep., 



Are distinguished from all the true siluri, by having 

 no radiated fin upon the back, but only a small adipose 

 one upon the tail, and by wanting altogether the 

 spine to the pectorals, whose rays are entirely soft. 

 Their head, as well as body, is covered with a smooth 

 skin ; their teeth are small and crowded, and disposed, 

 both above and below, on a broad crescent, there are 

 seven branchial rays ; their jaws and viscera resemble 

 those of the siluri. 



But one species is known with six barbels, the 

 head less bulky than the body, which is inflated in 

 front. It is the famous electric silurus of the Nile and 

 of Senegal. Silurus electricus, L., Geoffr., Poiss. d'Eg. 

 pi. xii. f. 1. Brousson. Ac. des Sc. 1T82. The Raasch, 

 or Thunder, of the Arabs, which gives, like the 

 Torpedo and the Gymnotus, electrical commotions. 

 It appears that the seat of this faculty is a particular 

 tissue situated between the skin and the muscles, and 

 which presents the appearance of an adipose cellular 

 tissue, abundantly provided with nerves. 



Aspredo, Lin. (fourth and sixth Ed.) Platystacus l , Bl., 



Exhibit very peculiar characters in the flattening of 



1 Under this name of Platystacus, Block unites Plotosus and 

 Aspredo ; Lacep. leaves the Aspredo with Silurus, but makes a dis- 

 tinct genus of Plotosus. 



N.B. We must remove from the whole of this great genus 

 Silurus : 1. the Silurus cornulus, Forsk. p. 66, which has furnished 



