NO. 6 ANNELIDA, ONYCHOPHORA, AND ARTHROPODA SNODGRASS 85 



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Fig. 37. — Embryonic and adult segmentation of Liiiuilus. (A-E from Iwanoff, 

 1933) 



A, Linmlns nwluccamis Linn., germ band with mesoderm divided into four 

 postoral somites, cephalic lobes not yet differentiated from blastoderm. B, same, 

 embryo with nine pairs of appendages, cephalic lobes (Pre) present. C, first 

 instar larva, segments of opisthosoma indicated by internal mesoderm bands 

 before moulting. D, first instar larva before moulting stage. E, second instar 

 larva. F, Liviulus polyphemus Linn., young adult, veqtral view, prosomatic 

 appendages removed, showing radial position of their bases around the central 

 mouth. 



Acr, acron, derived from procephalic lobes of embryo; Au, anus; Chi, 

 chilarium; CIil, chelicera; csp, caudal spine; dbl, doublure; dO, dorsal ocellus; 

 E, compound eye; fg, fixigene ; gib, glabella; I-VI, first six somites; L, leg; 

 Ig, libragene ; Lm, labrum ; Mth, mouth ; Opl, genital operculum ; Pdp, pedipalp ; 

 Pre, procephalic lobe; vO, ventral ocellus. 



