PLATE I. 



PAGE 



Fig. 1. Halichondria peUicidata, seen horn in iront ; o, oscula ; natural size, . 5 



Fig. la. Seen from behind ; natural size. 



Fig. 2. Reniera aquxductus, Y&x. infundihularis ; natural size, . . .16 



Fig. 3. Reniera subglobosa : natural size, . . . • .17 



Fig. 3a. View of portion of the inside ; natural size. 



Fig. 4. Reniera implexa, var.; natural size, . . . . . 15 



Fig. 5. Halichondria latrunculioides ; o, oscula; p.a, raised pore-areas; natural 



size, .....••• 6 



Fig. 5a. One of the raised pore-areas ; x 1 2. 



Fig. 6. Reniera tu/h ; natural size, . . . ■ • .18 



Fig. 6a. Vertical section ; natural size. 



