PLATE XVIII. 



Fifi. i.--Reniera scoiti Kirkp., nat. size, p. oL!. 



Fro. la. — Surface, showing pores ( X 2). 



Fig. lb. — Vertical longitudinal section ( X >^). 



Fiu. -1. — Renieret scotti,. another specimen. 



Fig. 8. — Renma dnncoi Topsent, nat. size, p; ■H;!. 



Fig. 4. — Petrosia flsMata Kirkp., nat. size, p. 51. 



Fig. 4a. — Surface of same ( x 4). 



Fig. 4b.— Section (x 8). 



Fig. 5. — Oceanapia tantula Kirkp., fragments of fLstulae, p. 



Fig. 5a.— Closed end of one of the fistulae ( x 4). 



Fig. 5b, -Section ( x 8). 



