OF THE SPONGIAD.E. 279 



FIG. 



310. A piece of reticulated kerato-fibrous tissue supporting 



the dermal membrane of one of the species of the 

 common West Indian sponges of commerce. 

 X 108 linear. Pages 108, 109. 



311. A small portion of the quadrilateral siliceo-fibrous 



network of the dermis of Farrea occa, Bowerbank, 

 MS., showing the double series of entirely spined 

 spicular organs projected from its angles. X 108 

 linear. Page 104. 



CILIA AND CILIARY ACTION. 



312. A longitudinal section of the intermarginal cavities of 



Grantia coiupressa, showing the cilia and their 

 basal cells in situ. X 500 linear. Pages 82, 105, 

 129, 130, and 163. 



313. A view -of a small portion of the inner surface of 



Grantia compressa, exhibiting the oscula open, 

 and the appearance presented at their orifices by 

 the cilia within in action. X 500 linear. Pages 

 105, 129, 130 and 163. 



314. Detached cilia and tessellated cells from the interior 



of the intermarginal cavities of Grantia coiupressa. 

 X 1250 linear. () A cilium in repose. (&) One 

 in the position of action, (r) Detached cells. 

 Pages 82 and 129. 



REPRODUCTIVE ORGANS. 



315. A small piece of a fibre of the skeleton of one of the 



common Bahama sponges of commerce, with nu- 

 merous ova imbedded in its surface. X 400 

 linear. Pages 81 and 134. 



316. A small piece of the fibre represented by Fig. 315, 



exhibiting the varieties in form and proportion of 

 the ova. X 1250 linear. Pages 81 and 13t. 



