OF THE SPONGIAD.E. 285 



FIG. 



358. POLYMASTIA ROBUSTA, Bowerbank. A view of a small 



portion of the side of one of the large cloacae, ex- 

 hibiting the structure and mode of disposition of 

 the longitudinal skeleton fasciculi. X 25 linear. 

 Page 178. 



359. HALYPHYSEMA TUMANOWICZII, Bowerbank. A com- 



plete sponge, based on the stem of a Zoophyte, 

 exhibiting the irregular longitudinal disposition 

 of the skeleton spicula. X 175 linear. Page 

 179. 



300. CIOCALYPTA PENICILLUS, Bowerbank. Representing 

 a longitudinal section through the central axis of 

 one of the elongate cloacal portions of the sponge, 

 exhibiting the central column with the small 

 cylindrical pedicels or short fasciculi of closely 

 packed spicula, each terminating at the inner sur- 

 face of the dermis of the sponge, natural size. Page 

 181. 



361. A section of the speciuien represented by Fig. 360, 

 at about the middle of the cloacal column, ex- 

 hibiting the mode of the radiation of the distal ends 

 of the small pedicels on the inner surface of the 

 dermis. X 25 linear. Page 131. 



302. TETHEA CRANIUM, Lamarck. A portion of a thin sec- 

 tion at right angles to the surface, exhibiting the 

 upper portion of the radiating fasciculi ; their 

 terminations being projected beyond the dermal 

 surface of the sponge. X 50 linear. a, porrecto- 

 ternate external defensive spicula ; b, the mode in 

 which they are supported by buttresses of spicula 

 beneath the surface of the sponge ; c, the recurvo- 

 ternate spicula. Pages 25, 124 and 183. 



363. HALICNEMIA PATERA. A portion of a section at 

 right angles to the surface, exhibiting the mode of 

 disposition of the spicula of the skeleton. X 25 

 linear. Page 184. 



