331 



PLATE XCI. 



IsoniCTYA EUGOSA, Boiverhanlc. 



Fig. 1. — Represents the type-specimen. Natural 

 size. 



Fig. 2. — One of tlie subfusiformi-acerate tension 

 spiciila of tlio dermal membrane. X 250 linear. 



Fig. 3. — A large-sized cqui-ancliorate retentive 

 spiculum from tlie dermal membrane. X 530 linear. 



Fig. 4. — One of tlio largest of the simple bihamate 

 retentive spicula of the dermal membrane. X 530 

 linear. 



Fig. 5. — An average-sized acuate basally-s]oined 

 skeleton spiculum. X 250 linear. 



Leuc'ONIa Somesii, Bowerhank. 



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 fistula3 only. Natural 

 size. 



Fig. 8. — A young specimen in a more advanced 

 stage of development, with large cloacal fistula? pro- 

 jected from a basal mass. Natural size. 



Fio'. 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 hnear. 



Fio'. 10. — An acerate defensive spiculum from the 

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



Fio-. 11. — One of the large, slender, acerate, pro- 

 cumbent spicula from the large cloacal fistula?. 

 X 250 linear. 



