434 



CEUSTAOEA. 



present undergo further segmentation. Many parasitic Copepoda, 

 however, pass over the series of Nauplius forms, and the larva, as 

 soon as hatched, undergoes a moult, and appears at once in the 

 youngest Cyclops form, with antennae adapted for adhering and 

 mouth parts for piercing (fig. 344). From this stage they undergo 



a retrogressive metamorphosis, 

 in which they become attached 

 to a host, lose more or less com- 

 pletely the segmentation of the 

 .* body which grows irregular 

 in shape, cast off their swim- 

 ming feet, and even lose the 

 eye, which was originally pre- 

 sent (Lernceopoda). The 

 males, however, in such cases 

 often remain small and 

 dwarfed, and adhere (fre- 

 quently more than one) firmly 

 to the body of the female in 

 the region of the genital open- 

 ing (fig. 345). 



In the Lerncea (fig. 346) 

 such pigmy males were for a 

 long time vainly sought for 

 upon the very peculiarly 

 shaped body of the large female 

 (fig. 346, c, d) which carries 

 egg tubes. At last it was 

 discovered that the small 

 cyclops-like males (fig. 346, a), 

 lead an independent life, and 

 swim about freely by means 

 of their four pairs of swim- 

 ming feet; and that the fe- 

 males (fig. 436, 6), in the 

 copulatory stage resemble the 

 males, and that it is only 

 after copulation that they 

 (the females) become parasitic 

 and undergo the considerable 

 increase in size and modification of form which characterises the 

 female with egg-tubes. 



FIG. 345. The t\vo sexual animals of Chandra, 

 canthus gibbosm magnified about six diameters. 

 a, Female seen from the side; b, from the 

 ventral surface with adhering male ; c, male 

 strongly magnified. An', Anterior antennae ; 

 An'', antennae for attachment; F', F", the 

 two pairs of feet; A, eye; Ov, egg-tubes; 

 Oe, oesophagus ; D, intestine ; M, mouth 

 parts ; T, testis ; Vd, vas deferens ; Sp, 

 spennatophore. 



