343 



PLATE XCTI. 



IsODicTYA TUMiTLOSA, BowcrbanJc. 



Fig. 1 — Represents tlie type-specimen. Natural 

 size. 



Fig. 2. — A skeleton spiculum. X 320 linear. This 

 figure also represents tlie acuate entirely spined tension 

 spicula of tlie porous areas. 



Fig. 3. — One of tlie simple biliamate retentive 

 spicula of tlie dermal membrane. X 530 linear. 



Fig. 4. — A contort biliamate retentive spiculum 

 from tlie dermal membrane. X 530 linear. 



Fig. 5.— One of the very minute simple biliamate 

 retentive spicula. X 530 linear. 



Fig. 6. — A bidcntate equi-ancliorate retcntivo 

 spiculum of tlic larger size. X 530 linear. 



Fig. 7. — A spineless acerate spiculum witli sonii- 

 liastate termination from tlic skeleton structure. X 

 320 linear. 



Batteeseyia Bitoklandi, Bowerhanh. 



Hymeniacidon Bucldandi. Vol. ii, p. 227, Mou. Brit. 



SpongiadtG. 



Fig. 8. — Represents a section of the type-specimen 

 at right angles to the external surface, exliibiting the 

 mode of disposition of the skeleton spicula. X 60 

 linear. 



Hymeniacidon Aldousii, Bowerbanlc. 



Fig. 9. — Represents the type-specimen of the species. 

 Natural size. 



Fig. 10. — An acuate skeleton spiculum. X 260 

 linear. This figure also represents the spicula of the 

 dermal membrane. 



Fig. 11. — A very slender form of the skeleton 



