Willey. — Economic History of Copepods 321 



character, Linnaeus placed all the Entomostraca known up to his 

 time under the genus Monoculus (1766, Systema Natures, 12th 

 edit.). The leading copepod of the sea over the fishing banks 

 of Norway, a widely distributed species now known as Calanus 

 finmarchicus, was originally named Monoculus finmarchicus in 

 1765. 



The name Copepoda ("oar-footed") originated in France 

 (1840) and is applied to those Entomostraca, inhabiting 

 fresh and salt water, which have five pairs of two-branched 

 swimming feet on the forebody, and a five-jointed footless 

 abdomen terminating in a forked tail. Fertilization is effected 

 by means of spermatophores attached externally by the male 

 to the genital segment of the female; the eggs are carried about 

 in one or two ovisacs (according to the species), or are shed 

 directly into the water. The young hatch out as minute free- 

 swimming larvae provided with three pairs of swimming 

 appendages corresponding to the future feelers and mandibles. 

 These larvae are known collectively, irrespective of specific dis- 

 tinctions, as nauplii or nauplius-larvae. After shedding the 

 outer skin or cuticle, the nauplius becomes transformed into a 

 metanauplius and after further exuviation the so-called cope- 

 podite stages begin, each stage being preceded by a casting of 

 the cuticle. Altogether there are six copepodite stages, the last 

 of which is the adult form. But the adult form still grows and 

 expands before reaching complete maturity. 



While the zoological history of the Entomostraca began 

 about 1669 and the foundation of their classification was laid 

 down in 1766, their economic history dates only from 1867, 

 when their importance as fish-food in general and herring-feed 

 ("Sildeaat") in particular was estabhshed by a Norwegian car- 

 cinologist, Axel Boeck. 



The identification of these little animals, whose length ranges 

 from half a millimetre to five and even eight millimetres, natur- 

 ally preceded their nutritive valuation, and unless the original 

 description is adequate and subsequent determinations correct, 

 work upon them is apt to be thrown away. Much praiseworthy 



