The Nematognathi, or Catfishes 397 
a few cases the adipose fin develops an anterior spine and 
occasionally supporting rays. 
All the Nematognathi are carnivorous bottom feeders, de- 
vouring any prey they can swallow. Only a few enter the 
sea, and they occur in the greatest abundance in the Amazon 
region. Upward of 1200 species, arranged in 150 genera, are 
recorded. They vary greatly in size, from two inches to six feet 
in length. All are regarded as food-fishes, but the species in 
the sea have very tough and flavorless flesh. Some of the 
others are extremely delicate, with finely flavored flesh and a 
grateful absence of small bones. 
Families of Nematognathi—According to Dr. Eigenmann’s 
scheme of classification,* the most primitive family of Nema- 
tognathi is that of Diplomystide, characterized by the pres- 
ence of a well-developed maxillary, as in other soft-rayed fishes. 
The single species, Diplomystes papillosus, is found in the waters 
of Chile. 
Similar to the Diplomystide in all other respects is the great 
central family of Siluride, by far the most numerous and im- 
portant of all the divisions of Nematognatht. 
The Siluridz.—This group has the skin naked or imperfectly 
mailed, the barbels on the head well developed, the dorsal short, 
inserted forward, the adipose fin without spine, and the lower 
pharyngeals separate. All the marine catfishes and most of 
the fresh-water species belong to this group, and its members, 
some 700 species, abound in all parts of the world where cat- 
fishes are known—‘‘a bloodthirsty and bullying race of rangers 
inhabiting the river bottoms with ever a lance at rest and ready 
to do battle with their nearest neighbor.” 
The Sea Catfish.—In the tropical seas are numerous species of 
catfishes belonging to Tachysurus, Arius, Galeichthys, Felich- 
thys, and other related genera. These are sleek, silvery fishes 
covered with smooth skin, the head usually with a coat of mail, 
pierced by a central fontanelle. Some of them reach a con- 
siderable size, swarming in sandy bays. None are valued as food, 
being always tough and coarsely flavored. Sea birds, as the 
pelican, which devour these catfishes are often destroyed by 
* A Revision of the South American Nematognathi, 1890, p. 7. 
