331 



PLATE XCI. 



ISODIOTYA KUGOSA, Bowerbank. 



Fig. 1. Represents the type-specimen. Natural 

 size. 



Fig. 2. One of the subfusiformi-acerate tension 

 spicula of the dermal membrane. X 250 linear. 



Fig. 3. A large-sized equi-anchorate retentive 

 spiculum from the dermal membrane. X 530 linear. 



Fig. 4. One of the largest of the simple bihamatc 

 retentive spicula of the dermal membrane. X 530 

 linear. 



Fig. 5. An average-sized acuate basally-spined 

 skeleton spiculum. X 250 linear. 



LEUCONIA SOMESII, BowerbanL 



Fig. 6. Represents the type-specimen in a fully- 

 developed condition. Natural size. 



Fig. 7. A very young specimen of the species, 

 consisting of a congeries of fistulse only. Natural 

 size. 



Fig. 8. A young specimen in a more advanced 

 stage of development, with large cloacal fistulas pro- 

 jected from a basal mass. Natural size. 



Fig. 9. One of the small cloacal fistulas covered 

 with long, slender, acerate, external, defensive spicula, 

 from the surface of the type-specimen represented by 

 fig. 6. X 36 linear. 



Fig. 10. An acerate defensive spiculum from the 

 cloacal organ, represented by fig. 9. X 250 linear. 



Fig. 11. One of the large, slender, acerate, pro- 

 cumbent spicula from the large cloacal fistula?. 

 X 250 linear. 



