PISCES. 217 



New York, and in those of the Mississippi valley. They will probably be 

 discovered in the eastern rivers (in the Hudson at least), when their ichthy- 

 ology has been more fully studied. Marine forms are met with in 

 Galeichthys, Arius, and Bagrus, the former characterized by the high dorsal 

 and pectorals. 



South America exhibits some Siluroids of especial interest. Conspicuous 

 among these are Arges cyclopum, or Pimelodus cyclopum of Humboldt, 

 and Brontes prenadilla, which inhabit the highest regions in which fish are 

 known to live. They are found in Quito, at elevations of more than 16,000 

 feet above the level of the sea, living in the streams running down the sides 

 of Cotopaxi and Tungaragua. The most interesting fact in the history of 

 these fishes is, tJiat they are frequently ejected from the craters of the above- 

 mentioned volcanoes, in immense numbers ; the supply being probably 

 derived from the subterranean lakes in the body of the mountains. Our 

 space w^ill not permit us to mention any other members of this interesting 

 family, excepting the Malapter,us electricus, the Silurus electricus of older IAJ^I 

 authors. This species is characterized generically by the absence of the 

 first dorsal, the adipose dorsal alone existing, as also by the possession of an 

 electric apparatus or battery, somewhat intermediate in character between 

 those of Gymnotus and Torpedo, although of much finer texture. The 

 whole body beneath the integuments is inclosed by the apparatus in two 

 layers of great compactness, and at first sight suggesting a deposit of fat. 

 A dense fascia separates the battery from the muscular system. The cells, 

 formed by transverse and longitudinal fibrous partitions, are rhombic in 

 shape, and exceedingly minute. The nerves of the outer organ come from 

 branches of the fifth pair of nerves, the inner organ is supplied by the inter- 

 costal nerves. The direction of the current is probably from the head to 

 the tail ; the cephalic extremity being positive, and the caudal negative. 



We now come to the third order, Pharyngognathi, of our classification, 

 divided into two sub-orders, Malacopterygii, or soft finned forms, and 

 Acanthopterygii, or spiny finned. The only family belonging to the first 

 division is that of the 



ScoMBEREsociD^, characterized by a structure intermediate between 

 that of EsocidcB and Scombridcs. The body is greatly elongated, and the 

 jaws produced into long, very narrow beaks. The scales are minute, and 

 hardly apparent in some species. The more conspicuous genera are Belone 

 and Scomhei'esox ; the former having a considerable external resemblance to 

 the gar-fish, Lepidosteus, but with very minute soft scales, the latter having 

 the posterior portion of the anal and dorsal divided into finlets, as in tlie 

 mackerel, in other respects like Belone. This last mentioned fish is repre- 

 sented by several species in North America, one of which, B. truncata, 

 occasionally penetrates the Atlantic rivers, as the Delaware and Susque- 

 hanna, and is known also as the silver-gar, or bill-fish. Neither genus is 

 of any economical value. Inconspicuous in this respect, also, are the 

 tamilies CnROMiDiE, Cyclo-Labrid^, and CTENO-LABRiOiE, sufficiently cha- 

 racterized by the spurious fin rays, and the ordinal characteristics. The 

 old family of LabridcB, including the two latter sub-divisions, which differ 



421 



