PLATE V. 



Fig. I. Group of six spicules, a, b, c, d, e, f, of Isis hippiiris Linn. •; 120. 



Fig. 2. Group of five spicules, a, b, c, d, e of Isis i-eticiilata Nutting X 120. 



Fig. 3. Group of three spicules, a, b, c, of Ceratoisis wrighti Nutting X 64. (Approximately one half of 



each spicule is shown). 



Fig. 4. Group of three spicules, a, b, c, of AcancUa sibogic Nutting :< 120. 



Fig. 5. Group of four spicules, a, b, c, d, of JMopsea flava Nutting X 120. 



Fig. 6. Group of three spicules, a, b, c, of Acanella weberi Nutting X 120. 



