NO. 6 ANNELIDA, ONYCHOPHORA, AND ARTHROPODA SNODGRASS 



dO 



III 



-25a 

 5b 



Fig. 47. — Segmental analysis of Xiphosurida (Liviulus polyphemus Linn.). 



A, young adult, dorsal surface. B, ventral surface of dorsal carapace, show- 

 ing muscle attachments and series of dorsal apodemes, or entapophyses (from 

 Benham, 1885, with dorsal ocelli added). C, ventral surface of prosoma, show- 

 ing segmentation as indicated by position of leg bases. D, dorsal surface of 

 opisthosoma, with segmentation indicated. E, theoretical approximate segmen- 

 tation of prosoma. 



Acr, acron; Ap, tergal apodemes (entapophyses) ; Chi, chilarium ; Chi, chelic- 

 era ; dbl, doublure (ventrally inflected part of acron); dO, dorsal ocellus; E, 

 compound eye; fg, fixigene ; fs, facial suture; I-XIV, postoral somites; L, leg; 

 Ig, libragene ; Lm, labrum ; Mth, mouth ; Opl, genital operculum ; p, external 

 pits of tergal apodemes ; i^a, b, f, dorsal attachments of tergo-sternal muscles 

 of opercular and gill somites ; 20a, b, f, dorsal attachments of anterior muscles 

 of opercular and gill appendages; 25a-e, 28, dorsal attachments of tergo-coxal 

 muscles of prosomatic appendages. 



