112 



ZOOLOGY 



(B, ms. nph.) from which the permanent kidney is formed in must 

 of the lower Craniata. The mesonephric nephridia open at one 



CLTV 



FIG. 747. Diagrams illustrating the development of the urinogenital organs of Craniata. 

 A, development of proiiephros and segmental duct/; B, atrophy of pronephros, development 

 of mesonephros ; C, differentiation of pro- and meso-nepJudc ducts ; D, development of meta- 

 iiephros, male type; E, female type. al. II. allantoric Wadder ; an. anus; cl. cloaca; gon. 

 gonad ; int. intestine; m. e. Malpighian capsule; ms. n. d. mesonephric duct; ms, ,//>/,. 

 mesonephros ; mt. n. d. metanephric duct ; mt. nph. metanephros ; nst. nephrostorne ; or 

 ovary; p.n.d. pronephric duct; p. nph. pronephros; sg. d. segmental duct; t. testis : <. e. 

 vasa effereutia. 



end into the segmental duet (sg. rf.), at the other, by ciliated 

 funnels (nst.), into the coelome : a short distance from the funnel 



