ON THl'; DIPLOOHORDA. 375 



On the Diplochorda. 



III. The Early Development and Anatomy of Phorouii 

 Buskii, McI. 



By 



Ai-tlitu- T. Mastci-iuaii, I»I. A. (Cantab.), D.Sc.(JLoiid. 



and St. A.), 



Lecturer on Zoology in the New Medical School, Ediubur-li. 



With Plates 18—21. 



LiTEEATUEE. 



Dr. Dyster (6) appears to have first published observations 

 upon th e de velopmeu t of P h o r o n i s (P. h i p p o c r e p i a) . The 

 anatomical part of his paper is principally concerned with 

 the alimentary and vascular systems, and parts of this will 

 be referred to later on. 



He watched the whole process of oviposition, the passage 

 of the eggs through the nephridia (the 'Hiollow ridge '^) and 

 their deposition in the inner space of the lophophore. To 

 the wall of this ridge they adhere by a glutinous exudation. 

 "They are voided alternately through each ridge (ne- 

 phridium) and form a compact white mass, separable only with 

 considerable difficulty on each side ol the space in the con- 

 cavity of the lophophore, shadowed over by the interlacing 

 extremities of the inner tentacles.^' He states, further, that 

 the larva " quits the parent nest when about forty-eight 

 hours old." He figures three larv^ at different stages, the 

 latest having one pair of tentacles. Both the figures and 

 description clearly show that he mistook the anal end for the 



VOL. 43, PART 2. — NKW SERIES. CC 



