216 ZOOLOGY. 



cataractus, or the fall fish of Pennsylvania, attains to a considerable size, 

 perhaps larger than that of any other allied form in this country ; specimens 

 have been seen nearly two feet in length, and weighing several pounds. 

 This size is, however, exceeded by many of the European species. The 

 peculiar genus Exoglossian is characterized by a trilobed lower jaw, the 

 middle lobe formed by the extremity of the lower jaw, the lateral by cartila- 

 ginous expansions. Another interesting sub-family, embracing several 

 genera and many species, is that of the Siickej-s, or Catastomi, known by 

 the highly fleshy lips, which can be applied to any object like a sucker. 

 The pharyngeal teeth are columnar or prismatic, not hooked and truncated. 

 Thev are found abundantly throughout North America ; and different species 

 are known by the various names of carp, sucker, mullet, buffalo-fish, red- 

 horse, &c. PL 81, figs. 6, 7, represent Cobitis fossilis and E. harbalula, 

 European species of a form not found in North America. 



The concluding family of the order Malacopteri, or Physostomi, is found 

 in the Silurid.e, represented in North America by the catfish. P'ishes of 

 this family have the skin either naked, and covered with a slimy secretion, 

 or provided with osseous plates of various number and shape. The head 

 is usually depressed, and provided with a variable number of barbels. In 

 most, there is a second and adipose dorsal, sometimes confluent with the 

 caudal. The first rays of the dorsal and pectoral fins are generally enlarged 

 into strong spines ; and the pectoral spine is capable of being inflexibly 

 fixed, by peculiar mechanism, in a direction perpendicular to the axis of 

 the body. The edge of the mouth is formed by the intermaxillaries sus- 

 pended from the sides of the ethmoid, which enters into the outline of the 

 mouth, forming the superior median portion. The sub-operculum is absent 

 in the whole family. 



Species of this polymorphous family are found distributed throughout the 

 globe. In Europe, however, there is found but one species, the Silurus 

 glanis, or sheat fish. This species, interesting from the fact of its being the 

 largest fresh-water fish in Europe, the sturgeons excepted, is most abundant 

 in central Europe, its existence in England being hypothetical. The weight 

 has been known to exceed lOOlbs., in this respect equalling some of the 

 American Siluridce. It differs from the North American species in the 

 absence of a posterior adipose dorsal, in the very small true dorsal, and 

 in the very long anal. Other species of this restricted genus, Silurus, are 

 found in various parts of Asia, and perhaps Africa, but not in America. 

 The American forms are highly varied, those of the northern continent, 

 however, being quite uniform in structure. The two most conspicuous 

 fresh- water genera are Pimelodus and Notui^us ; the former with a distinct 

 adipose dorsal, the latter with this dorsal confluent with the caudal. 

 Numerous species of Pimelodus (cat-fish, horned-pout, bull-head) occur 

 in the various waters of North America, some of which acquire a large 

 size. One species, from the Mississippi, has been known to weigh over 

 lOOibs. The flesh of many species is highly prized, owing to its sweetness 

 and freedom from bones. The genus Noturus, known provincially as stone 

 cat-fish, embraces but few species, found in the Atlantic streams south of 

 420 



