NO. 10 



CRUSTACEAN METAMORPHOSES — SNODGRASS 



23 



The genus Calanus, a typical free-swimming marine copepod of 

 the suborder Gymnoplca, hkewise develops from nauplius to adult 

 by ordinary anamorphic growth without any metamorphic changes 



Fig. 8. — Copepoda: Podoplea. Developmental stages and adult of Cyclops. 

 (A-F from Dietrich, 1915; G from Claus, 1863). 



A, Cyclops strenuiis Fischer, nauplius, 0.119 mm. B, same, first metanauplius. 

 C, same, second metanauplius. D, same, third metanauplius. E, same, fourth 

 metanauplius. F, same, first copepodid, 0.303 mm. G, Cyclops coronatus Claus, 

 adult female with eggs, 3.50 mm. 



I Ant, first antenna; 2Ant, second antenna; iL, 2L, sL, legs; Md, mandible; 

 iMx, sMx, first and second maxillae ; Mxpd, ma.xilliped. 



adaptive to different ways of living at different stages. The life history 

 of the common Calanus finmarchicus has been described by Lebour 

 ( 1916) . The first six instars the author calls nauplii, but some of them 

 would ordinarily be regarded as metanauplii, since two posterior 

 segments and indications of a third segment are said to appear in the 



