486 EDWIN S. GOODRICH. 



genital cells of the adult. It can hardly be doubted that 

 primitively the renal organs (organs of Bojanus, nephridia of 

 authors) functioned as genital ducts. Such is, indeed, still the 

 case in Chsetoderma, the Neomenians, and the Zygobranchia. 

 Also in the most primitive Lamellibranchs, such as Nucula 

 and Solenomya, the peritoneal funnels still retain their 

 original function. As Pelseneer has shown (86), gradually a 

 separate genital duct has been split oflF, which in Anodon, 

 Cardium, &c., opens independently. Intermediate stages are 

 found in such forms as Pecten, and Spondylus, where the 

 genital cells are shed into the kidney itself; and in Area, 

 Ostrea, &c., where the kidney and genital duct open into a 

 common cloaca. Likewise in the Chitons a separation has 

 taken place of the genital region of the coelom from the renal ; 

 the gonad then acquires special ducts, which may not be 

 homologous with peritoneal funnels. In the Cephalopoda, 

 although the coelom remains continuous, special apertures serve 

 for the escape of the genital cells ; whether these should be con- 

 sidered as a second pair of peritoneal funnels is also doubtful.^ 

 (The aberrant form Rhodope veranii would appear to be 

 amongst the Mollusca, if it be really of that class, the only one 

 which retains true nephridia in the adult. It is provided with 

 a pair of branching tubes, opening by a common pore, and 

 ending internally in flame-cells. The coelomic or genital fol- 

 licles, ovarian and testicular, are small and numerous. Their 

 ducts join to a common hermaphrodite duct, which again di- 

 vides into two openings by male and female pores [43, 12].) 



DiNOPHILUS. 



For our purpose it will be convenient to treat this genus 

 separately, and not with the Archiannelida which will be in- 

 cluded with the Polychseta. It is of great interest, since, in 

 some species at least, the nephridia are metamerically repeated 

 whilst the coelom is represented by a single pair of genital 

 follicles. 



1 Such a case may be compared to that of certain Nemertiucs, where nu- 

 merous genital follicles and as many genital ducts are present in one segment, 

 and to the similar arrangement in the Vertebrates. 



