THE SURF-FISH FAMILY. 279 



"EiVER Perch" {Hysterocarpus Traslci, Gibbons). — This species very often reaches the weight 

 of about half a pound. It is confined to the fresh water, being found in the Sacramento and San 

 Joaquin Rivers, and other streams as far southward at least as San Luis Obispo. It is sent in 

 small numbers to the markets of San Francisco, and is chiefly eaten by the Chinese. 



91. THE MOHARRA FAMILY— GERRID^. 



This family is represented on our eastern coast by four species, all of which are very small 

 and of little consequence except as food for larger fishes. 



Gerres argenteus, first discovered by Professor Baird at Beesley's Point, New Jersey, appears 

 to be common from North Carolina to New Jersey, and has been, within two or three years, 

 observed at Wood's Holl, Massachusetts. 



G. harengulus and G. homonymus occur in the Gulf of Mexico. In the Bermudas there are 

 three species of this genus; these are known by the names "Shad" and "Long-boned Shad." 

 They are seined in great numbers, and constitute an important article of food. 



92. THE THREAD-FISH FAMILY— POLYNEMID^. 



The family Polynemidce is remarkable by reason of the elongate filaments which are developed 

 in connection with the pectoral fin. Giinther has remarked: " Their eyes are large, but generally 

 obscured by a filmy skin, so that these feelers must be of great use to them in helping them to 

 find their way to their food. It is evident, from the organization of these fishes, that they live in 

 thick water or muddy bottoms, such as are found near the mouths of great rivers." 



There are two or three species upon our coast, one of which, the "Thread-fish" of Pensacola, 

 Polynemus octonemus, is the subject of the following interesting observations by Mr. Stearns: 



" The Thread-fish is rather common at Pensacola in summer, and has not been observed else- 

 where in the Gulf by me. My first specimen was taken at the surface of the water in Pensacola 

 Bay, May 21, 1878. Later in the season I saw large schools of them in shoal water along the sea- 

 beach swimming towards the harbor mouth. On June 14 a very large school of them came into the 

 surf near Fort McEae, and large numbers were thrown ashore by the waves, until perfect wind- 

 rows of dead fish were found upon the sands. Sharks and other fishes were preying upon them in 

 the water, and vast numbers of sea-birds and buzzards awaited them on land. The individuals 

 composing this school were of various sizes, the majority being adults. (Several of these were 

 sent to the National Museum.) They were evidently moving towards the bay. Small schools 

 were seen during the months of July of that and the follow ing year." 



93. THE SURGEON-FISH FAMILY— ACANTHURID^. 



On the coast of Florida, as well as through the West Indies and in the Bermudas, occur two 

 species of this family, Acanthurus cceruleus and A. nigricans, generally known as "Doctor-fish" or 

 "Surgeon-fish." They are distinguished by slight differences of proportion and color. Each side 

 of the tail is provided with a sharp, lancet-like spine, which, when at rest, is received into a sheath, 

 but it may be thrust out at right angles to the body, and used as a weapon of offense; sweeping 

 the tail from side to side as they swim, they can inflict very serious wounds, and I have seen, in 

 the Bermudas, large fishes, confined in the same aquarium tank with them, covered with gashes 

 inflicted in this manner. They are available for food, but are more worthy of consideration on 

 account of their power of wounding the fishermen. The "Bone-fish" of Key West, according to 

 Stearns, belongs to this family and genus. It is quite common about the coral reefs of the South 

 Florida coast. 



