THE LARVA OF PHOXICIIILID1UM. 



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considerable degeneration before passing into that of the adult. 

 This is connected with its parasitic manner of life. 



On leaving the egg, the larva of Phoxichilidium possesses on the 

 whole the organisation of the usual six-limbed Pantopodan larva, 

 but is distinguished from the latter by the fact that the usually 

 hookdike terminal joints of the two posterior pairs of limbs are 



Fig. 73.— Various larval stages of Phoxichilidium (after Dohrn, Semper, and Adlerz). A, 

 free larva with the tendril-like fiagellae on the two posterior pairs of limbs (7/ and III). 

 B-D, larval stages found in Hydroid polyps. (A is more highly magnified than the other 

 figures.) 7-7/7, limbs; (?, intestine with its caeca; dr, glands of the first limb; li, larval 

 integument in the act of becoming detached ; n, ventral chain of ganglia ; >■, proboscis. 



much lengthened, and form long fiagellae, which can coil up like 

 tendrils (Fig. 73 A). These fiagellae, which may be much longer 

 than those represented in Fig. 73 (e.g., in Phoxichilidium femoratum, 

 (Hoek)), are probably used for attachment, the larvae winding them 

 round the Hydroids (e.g., Hydractinia, Podocoryne, TuLiilaria, 



