284 ANATOMY AND PHYSIOLOGY 



Order '2. SILICEA. 



Sub-order L. 

 FIG. 



353. PACHYMATISMA JOHNSTONIA, BowerbanJc. A section 



at right angles to the surface, exhibiting the irregu- 

 larity of the interstitial structures directly beneath 

 the dermal crust. X 50 linear. Page 172. 



354. GUODIABARRETTI, Bowerbcmk, MS. A section at right 



angles to the surface, exhibiting the radial disposi- 

 tion of the fasciculi of the skeleton, and a portion 

 of the dermal crust of the sponge. X 50 linear. 

 a, interinarginal cavities ; b, the basal dia- 

 phragms of the interinarginal cavities ; c, imbedded 

 ovaria forming the dermal crust of the sponge ; <-/, 

 the large patento-ternate spicula, the heads of 

 which form the areas for the valvular bases of the 

 interinarginal cavities ; e, recnrvo-ternate defensive 

 and aggressive spicula within the summits of the 

 great intercellular spaces of the sponge ; f, portions 

 of the interstitial membranes of the sponge, crowded 

 with minute stellate spicula ; y, portions of the 

 secondary system of external defensive spicula. 

 Pages 122, 169 and 171. 



355. ECIONEMIA ACERVUS, BowerbanJc, MS. A section at 



right angles to the surface, exhibiting the radial 

 fasciculi of the peripheral system, with the ternate 

 apices of the spicula directly beneath the dermal 

 membrane. X 50 linear. Page 174. 



356. ALCYONCELLUM ASPERGILLUIU, Qtioy et Gaimard 



(Euplectella Owen}. A portion of the surface of 

 the sponge, with its great inhalent areas ; a, the 

 primary longitudinal fasciculi ; b, the secondary 

 or transverse fasciculi. X 7 linear. Pas;e 177. 



O 



357. The oscular area of A. asperc/illum, with a marginal 



boundary, and the congregated oscula within, 

 natural size. Page 177. 



