254 



CRUSTACEA. 



fold covering the lateral parts of the posterior limb-rudiments. The 

 posterior end of the body, below the anal aperture which is now 

 becoming more distinct, is lengthened into two rounded f ureal 

 processes fringed with setae. Later MetanaupUus stages show a 

 change in the third limb, which has entirely lost the form of 



Fig. 117.— Three stages of developineiit of Eiiphmida (from Lano's Text-hool). A, Meta- 

 naupUus (after Metschnikoff). B, Calyptopis (after Claus). C, older Cahjptopis (after 

 Glaus). 1 and 2, first and second antennae ; 3, mandible ; i, 5, first and second maxillae ; 

 /, first pair of niaxillipedes ; ab, abdomen ; (rtj-as) first five abdominal segments ; a^, 

 sixth pair of pleopoda; an, anus; fs, frontal sensory organ; o, upper lip; «, paragnatha ; 

 til , thoracic segments. 



a swimming appendage and has developed into a masticatory blade 

 (mandible) with a greatly reduced palp. The shield-like fold has 

 now developed in the anterior region of the body, and thus 

 surrounds the cephalic portion of the larva (rf. the later stages, 

 I'ig. 117 ^ and C). In the posterior limbs, the first indication of 



