PLATE IV. 



All the Figures refer to Antedon rosacea. 



Figs. 1 and 3. The pinnule cysts (a) from an Antedon, dredged by the Liverpool Marine 

 Biological Committee, oflf Keumaes Bay, north coast of Anglesea. 



Fig. 2. Three deformities from an Antedon, dredged by the steamer " Vettor Pisani" at 

 Gibraltar, a, a groove-like deformity ; h, a pinnule-cyst ; c, an arm- 

 swelling. 



Fig. 4. The egg-like content of a pinnule-cyst from an Antedon, from Cumbrae. The 

 °right side (c) is drawn in surface- view ; the left side in optical section, 

 with the cortical layer (a) and the internal mass (b). 



Fig. 5. Longitudinal section through a pinnule deformity, showing the content (a), 

 enclosed in an uncalcified tissue (m). From the same locality as fig. 1. 



Fig. 6. Longitudinal section through a doubly deformed pinnule of an Antedon, from 

 Milford Haven, with four contents (or-d). 



(Figs. 1-3 are enlarged 5 times, figs. 4-6, 75 times.) 



