CALiGiD^f;. 257 



flat, and two-jointed. Second pair of foot-jaws of tw^o 

 articulations, and not in form of a sucking disc. Thoracic 

 segments uncovered. 



BihUograpltical History. — Linnaeus seems to be the 

 first author who takes notice of any animal belonging to 

 the genus Caligus. In his ' Fauna Suecica,' second edition, 

 1761, he shortly describes a species wdiich lives upon the 

 salmon and haddock, inhabiting the Norwegian seas. He 

 designates it ''Monocidus piscinus," and quotes Martin as 

 his authority for the habitat. In the same w^ork he de- 

 scribes a species of Pediculus, wdiich is found upon the 

 salmon also, calling it the " Pediculus Farionis.'' From 

 the general description of this little creature, and more 

 especially from its possessing two long ovarian tubes, it is 

 evident that it is a species of Caligus, and from its being 

 found upon the same species of fish, it would appear to be 

 closely allied to the Monoculus piscinus. In his ' Systema 

 Naturae,' 12th edition, 1767, he, indeed, distinctly affirms 

 this, and says it is " allied to the Monoculus piscinus from 

 its having two cylindrical bodies placed above the tail ;" 

 and Gmelin, in his edition of 1788, under the species 

 " Pediculus Farionis," remarks, " that it scarcely belongs 

 to this genus." Strom, in his ' Physiske og Oeconomisk 

 Beskrivelse over Fogderiet Sondmor,' 1762, describes and 

 figures what may be two species of Caligus, but which are 

 perhaps only the male and female, under the name of 

 Fiske luus, or Pediculi marini; and Baster, in his 

 ' Opuscula Subseciva,' 1765, describes and figures also 

 two or three different species of this genus, accompanied 

 with considerable details. Both of these authors repre- 

 sent the animal with its head downwards, and considered 

 the two long ovarian tubes as antennae, mistaking the tail 

 for the head. These figures and descriptions appear to 

 have misled Linnaeus ; for, notwithstanding his having 

 already described the animal correctly in his ' Fauna 

 Suecica,' he subsequently, in the 12th edition of his 

 ' Systema Naturae,' 1767, describes the Monoculus piscinus 



17 



