102 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



found in the mouth of this fish. This parasite appears to have been 

 first described by Latrobe, who proposed for it the name Oniscus pro}- 

 Qustator* Say subsequently referred it to the genus, CyniothoaA It is 

 known to the fishermen as the ''bug," "fish-louse," or "crab-louse," and 

 belongs to the order of Isopoda or equal footed crustaceans, familiar 

 examples of whicb are the whale-lice {Cijamus ceti, &c.) and the boring 

 shrimps {Limnoria Ugnorum) which riddle so completely the planks of 

 ships and other submerged timbers, or, better still, the " wood-lice,'^ 

 "saw-bugs," or "pill-bugs" to be found in any old cellar or wall and 

 under stones and logs which have lain for a time on damp ground. 

 Verrill and Smith f give twenty-three marine species for the coast of 

 Southern New England. Most of these inhabit the rocky shores, cling- 

 ing to the roots and branches of rock-weed or crawling among the rocks 

 near high-water mark. Three are parasitic, one upon the bluefish, one 

 upon the orange filefish ; a third was found by Professor Leidy in the 

 gill cavity of a hermit-crab [Gelasimus pugilator). Cymothoa prwgustator^ 

 resembles in its shape a large " pill-bug," the females reaching the length 

 of two inches, the males somewhat smaller ; they are provided with seven 

 pairs of legs, with claws sharply pointed and adapted for clinging to their 

 protector ; their color is dirty white. The females carry their eggs in a 

 large pouch on the under side of the body, formed by a series of large 

 scaly plates, where they are retained until the young are hatched and 

 large enough to care for themselves. The Cymothoa is not in any true 

 sense of the word a parasite, drawing nourishment from the fish to which 

 it attaches itself; it is commensal, stealing shelter and transportation, 

 but not subsistence, and Latrobe was very happy in his selection of a 

 specific name, for a Bomsm prcegustator was a foretaster, a cup-bearer, one 

 who tasted the meats and drinks before they were served on the table 

 of a prince. Clinging with its hook-like claws to the roof of the men- 

 haden's mouth, its back downward, its mouth in close proximity to the 

 front of the fish's upper jaw, it is in a very favorable location to take 

 toll from every mouthful of food which passes into thebrevoortian throat. 

 It may change its quarters at will, and when the fish is dead frequently 

 relaxes its grasp and crawls out of the mouth. Latrobe writes : " I have 

 sometimes succeeded in taking out the insect in a brisk and lively state, 

 but as soon as he was set free he immediately scrambled back into the 

 mouth of the fish and resumed his position." The presence of so bulky 

 a guest must greatly inconvenience the menhaden. I have taken from 

 the mouth of a fish nine inches long two of these crustaceans, a male 

 three-fo urths of an inch long, and a female measuring an inch and three- 

 ■ • A drawing and description of the Clupea Tyranaus and Oniscns PrcBgustator. Yj 

 Benjamin Henry Latrobe, F. A. P. S. Transactions of the American Philosopbical So. 

 ciety held at Philadelphia, for promoting useful knowledge. Vol. V , 1802, p. 77 pi. i 

 t Journal of the Academy of Natural Sciences of Philadelphia, Vol. 1., part II, 18ia 



p. 395. 

 i Report of the Commissioner of Fish and Fisheries for 1871-72, p. 567, 



§ See plate X. 



