280 



CRUSTACEA. 



The last stages of embryonic life already distinctly show the seg- 

 mentation of the body characteristic of the Phyllosoma larva. The 

 body falls into three sections, the anterior broadened section being 



still swollen by 

 the food - yolk 

 deposited in it, 

 and carrying 

 antennae, man- 

 dibles, and 

 maxillae. This 

 is followed by 

 a moderately 

 broad region, 

 consisting of 

 the segments 

 which carry the 

 maxillipedes 

 and ambulatory 

 limbs, and be- 

 hind this comes 

 a short narrow 

 abdomen. Be- 

 fore the Phyllo- 

 soma leaves its 

 embryonic en- 

 velope, certain 

 processes of de- 

 generation (Fig. 

 1*29) take place 

 in the body. 

 The second an- 

 tennae («") are 

 r educ e d t o 

 simple, mi- 

 branched pro- 

 cesses, and the 

 second maxillae 

 (mx") to short 

 ■■•■jointed stumps. The first maxillipede in Scyllams is altogether 

 lost, while in Palinurus it is retained in the form of a much reduced 

 vestige. The exopodites of the second and third maxillipedes 



Fio. 129.— Young Phyllosoma of Scyllarus (after Claus). Only the 

 basal joints of some of the limbs are drawn, a', first antenna ; 

 a", second antenna; d, antennal gland; a, brain; /, liver; md, 

 mandible; mx', lirst maxilla; mx", second maxilla; mf", second 

 maxillipede; mf", third maxillipede; », ventral chain of ganglia; 

 w, Nauplius eye; ol, upper lip; p', /', [>'", lirst three ambulatory 

 limbs. 



