PLATE XVI. 

 " ISODICTYA IN^QUALIS, Bowerlank. 



Fig. 1. Represents tlie type-specimen. Natural 

 size. 



Fig. 2. One of the subfusiformi-acerate tension 



O 



spicula. X 400 linear. 



Fig. 3. One of the short attenuato-acerate tension 



o 



spicula. X 400 linear. 



Fig. 4. A bidentate, equi-anchorate, retentive 

 spiculum. X 666 linear. 



Fig. 5. One of the bihamate retentive spicula. 

 X 666 linear. 



Fig. 6. A subfusiformi-acuate basally and apically 

 spinous skeleton spiculum. X 400 linear." 



. c 



ISODIOTYA IMPLICITA, Bowerbank. 



Fig. 7. Represents the type-specimen immersed 

 amid the branches of Nullipora polymorpha. Natural 

 size. 



Figs. 8. and 9. Two of the smaller specimens of the 

 species. Natural size. 



Fig. 10. A small portion of the subfasciculate 

 dermal membrane exhibiting the irregular mode of the 

 disposition of the tension spicula. X 308 linear. 



Fig. 11. One of the slender attenuate -acuate 



^j 



tension spicula, basally incipiently spinous, of the 

 dermal membrane. X 400 linear. 



Fig. 12. One of the stout attenuato-acuate basally 

 spinous spicula of the dermal membrane. X 400 

 linear. This figure also represents the skeleton 

 spicula. 



Fig. 13. Represents two of the bipocillate anchorate 

 retentive spicula of the dermal membrane. X 1166 

 linear. 



Fig. 14. One of the minute inequi-anchorate reten- 

 tive spicula. X 1166 linear." 



