470 Mr. J. H. Orton. Occurrence of Protandric [June 8, 



There would seem to be no doubt, therefore, of the permanence of the chains. 

 All the young ones, however, are motile, moving about by alternate exten- 

 sions and contractions of the flat muscular foot. 



Crepidula fomicata has hitherto been described as dioecious, with a 

 "marked sexual dimorphism" (2, p. 16), the males having been estimated 

 by Prof. Conklin as being on the average three-quarters the size of the 

 females. Those individuals were apparently called males, which had a 

 muscular, cylindrical, and tapering outgrowth, the penis, on the right side 

 of the head just behind the tentacle, as in fig. 2, <$ . Individuals having no 



Fig. 2.— Illustrations of the Five Categories of Individuals in C. fomicata. 



The animals were taken out of their shells and drawn from life (dorsal view), the 

 mantle being turned back over the visceral sac. The branchial filaments are drawn only 

 of the male, p., penis ; «., uterus ; p. r., rudimentary penis ; u. r., rudimentary uterus - f 

 a., anus : ant.f., anterior part of foot ; c.t, branchial filaments ; ep., epipodium ; ex. ap. u.> 

 external aperture of uterus ; /., foot ; «., intestine ; m. v., mantle vessel ; r. a., external 

 renal aperture ; sp.gr., sperm groove ; v.s., visceral sac. (Nat. size.) 



