24 



Figure 20: Pediveliger of Ostrea edulis L. (from Erdmann, 1935). 

 a — anus; aa — anterior adductor; acb — adoral ciliary band; ap — apical plate; be — buccal 

 cavity; bg — byssus gland; eg — cerebral ganglion; cplvc — cerebropleurovisceral connective; 

 cs — crystalline style; csg — crystalline style gland; dbg — duct of byssus gland; 

 dg — digestive gland; e — eye; es — esophagus; g — gut; gc — gill cavity; gr — gill 

 rudiment; lab — "mouth lobe" or "labium"; m — mouth; mc — mantle cavity; 

 mp — metapodium of foot; pa — posterior adductor; pate — postanal tuft of cilia; 

 pg — pedal gaglion; pig — pleural ganglion; pn — protonephridium; pocb — postoral ciliary 

 band; pp — propdium of foot; prcb — preoral ciliary band; rcr — rudiment of cerebrorenal 

 organ complex; rf — retractor of foot; rv — retractor of velum; st — stomach; stat — statocyst; 

 u — umbo; v — velum; vg — visceral ganglion. 



which have yet to undergo the last stage of development during metamorphosis 

 before they can become functional. 



Feeding : The digestive system of the pediveliger differs very little from 

 that of the veliger. The digestive gland enlarges and the small intestine elon- 

 gates, forming a long loop in many species. 



Respiration : A functional specialized respiratory system is absent in the 

 pediveliger. To the structures described earlier for the veliger, which facilitate 

 gas exchange, we may add the two to three gill filament processes which form 



