122 HIROSHl 0H8HIMA 



Right : Echinus-rudiment smaller than the left one. No 

 pediccllariao formed. 



[Case 6.] Echinus miliaris. MacBride, 1918 (15), 

 pp. 389, 848, 847, PI. vi, fig. 11. Reared in London. 



Left : axial sinus provided with a pore-canal and dorsal 

 pore. Lohed hydrocoele and amniotic invagination developed 

 normally. 



Right : axial sinus with a pore-canal and dorsal pore. 

 Hydrocoele smaller than that of the other side and no lobes 

 w(*re formed. Amniotic invagination absent. Two pedicel- 

 lariae developed. 



[Case 7.] Echinus miliaris. MacBride, 1918 (15), 

 pp. 888, 889, 848, PI. viii, figs. 18, 19. Reared in London. 



Left : axial sinus fused with that of the right side. Madre- 

 poric vesicle situated between the compound axial sinus and 

 the gut. Pore-canal and dorsal pore single. Echinus-rudiment 

 well-developed. Stone-canal double, probably formed by the 

 splitting of the string which had connected the hydrocoele 

 bud with the anterior coelom. 



Right : echinus-rudiment developed but, judging from the 

 figures, it was smaller than the left one. 



[Case 8.] Echinus miliaris. Culture 9, 'treated'. 

 The larva was fifteen days old when found and killed. 



Left : axial sinus well developed with a pore-canal and dorsal 

 pore. Madreporic vesicle rather rudimentary, but distinctly 

 seen lying close to the pore-canal. Stone-canal normal, leading 

 to the slightly-lobed hydrocoele. Amniotic invagination formed. 



Right : axial sinus and pore-canal rudimentary leaving no 

 visible lumen. Dorsal pore absent. No madreporic vesicle 

 found on this side. Hydrocoele as large as that of the left 

 side, but simply vesicular in shape. Stone-canal has in its 

 posterior part a distinct lumen and its calibre is as thick as 

 its left fellow ; but the canal passes into a solid cell-string as 

 it goes dorsad towards the vestigial axial sinus. No amniotic 

 invagination formed. 



(b) Left hydrocoele and its associated structure more or less 

 incomplete. Such is found verj' rarelj^ and hitherto any 



