THE OTOCYST OF THE PlXXIDjE. 



Be this as it may, the lobes are not all joined in a single mass. 

 In fact, all of the cases figured show two isolated groups. The 

 series of sections from which Fig. i was reconstructed shows that 

 this particular otocyst was formed by two separate invagiiiaiions 

 from the ectoderm. The tubes indicating their ectodermal 

 nature still persist, as illustrated in Fig. 4. The same ectodermal 



I 2 



FIGS, i and 2 are reconstructions of the two otocysts of a single specimen. 

 Note that each is composed of two separate groups of capsules. Note also that 

 the appearance is such as to suggest its origin through a process of budding. 



origion of the otocyst of another specimen, not here figured, is 

 demonstrated by similar ectodermal tubes. 



It is generally conceded that the otocysts of all mollusks are 

 ectodermal in origin, but it is unusual for their connection with 

 the ectoderm to remain intact in the adult. Such a connection 

 has not. up to this time been observed except in the primitive 

 unspecialized Protobranchia. 1 - y 



1 Drew, G. A., "Life History of Nucula delphinodonla," Quarterly Jour. Micr. 

 Set., Vol. 44, Part 3, new series. 



2 Lankester, E. Ray, "A Treatise on Zoology," Part V., page 18. 



