GEPHYREA 269 



Order Sipunculoidea, without prostomium in adult; chaetae 

 always absent, anterior part of body invaginable into posterior part ; 



m.retr. 



Fig. 198. Bonelliaviridis. A, Female. B, Male from nephridium of female. 

 After Spengler, C, Sipiinculus. From Shipley and MacBride. a. frilled 

 membrane surrounding the mouth; al. alimentary canal; al.' degenerate 

 alimentary canal of male; an. anus; an.v. anal vesicle; bt. brown tube 

 (nephridium); ch. position of chaetae; cil.gr. ciliated groove; cm. coecum of 

 gut; d.v. dorsal blood vessel; e. cut ends of intestine; g. anal glands; m.retr. 

 retractor muscle of anterior end; M. mouth; n.c. nerve cord; nephr. nephro- 

 stome; oe. oesophagus; o. ovary; op. ^ male reproductive aperture; pr. 

 greatly enlarged prostomium; sp. spermatozoa. 



anus dorsal and anterior; with a single pair of segmental organs 

 (brown tubes); no trace of segmentation even in the larva. 

 Sipunculus (Fig. 198 C) and Phascolosoma are British genera. 



