286 ANATOMY AND PHYSIOLOGY 



FIG. 



364. A portion of the section represented by Fig. 363, 



taken at a, X 108 linear. Pages 184 and 200. 



365. DICTYOCYLINDRUS RUGOSUs, Bowerbank. Represents 



a longitudinal section of half of a small branch, ex- 

 hibiting a portion of the axial column a, and the 

 peripheral system arranged in fasciculi, radiating 

 from it. X 50 linear. Pages 24 and 186. 



366. A longitudinal section through the axial column of 



Dictyocylindrus ramosus, showing the elongo-reticu- 

 late structure of the skeleton of the sponge. X 50 

 linear. Page 186. 



367. PHAKELLIA VENTILABRUM, Bowerbank. A longitu- 



dinal section of half of one of the primary radial 

 lines of skeleton structure, exhibiting the slender 

 secondary radiation of the skeleton. X 50 linear; 

 a, part of the axial column. Page 187. 



368. MICROCIONA ATRASANGUINKA, Bowerbank. A single 



mature pedestal of the skeleton, showing its struc- 

 ture and the proportions and positions of the ex- 

 ternal defensive spicula. X 175 linear. Pages 26 

 and 188. 



869. A section at right angles to the surface of Microciona 

 astrasanguinea exhibiting the mode of the disposi- 

 tion of the columns of the skeleton and the dermal 

 surface at a. X 108 linen r. Pages 26 and 188. 



370. HYMERAPHIA STKLLIFERA, Bowerbank. A section at 

 right .angles to the basal membrane, showing the 

 large bulbous skeleton spicula in situ, their apices 

 forming the external defences ; a, the stelliferous 

 internal defensive spicula elevated by a grain 

 of sand beneath the basal membrane. X 108 

 linear. Fig. 34, Plate T, represents one of this 

 form of spiculum. X 260 linear. Pages 27, 32, 

 325 and 189. 



