252 ANATOMY AND PHYSIOLOGY 



FIG. 



151. BIPOCILLATED EQui-ANCHoRATE. X 1166 linear. 



See Plate XXXVII. Each termination of the shaft 

 is developed equally in the form of a cup. They are 

 abundantly dispersed in a recumbent position on 

 the interstitial membranes of the sponge. From 

 an undescribed species of Desmacidon, which I 

 received from my late friend, Mr. Thomas Ingall. 

 Locality unknown. 



152. NAVICULOID SPICULUM. X 660 linear. See Plate 



XXXVII. From a new species of Hymedesmia in 

 the cabinet of Geo. Clifton, Esq., Freemantle, 

 Western Australia. I received a small portion of the 

 sponge mounted in Canada balsam. The spicula are 

 abundantly dispersed over the interstitial mem- 

 branes of the sponge, but principally in the vicinity 

 of the skeleton fasciculi. They vary to some extent 

 in form, but the one figured represents the general 

 structure. A keel like rib may occasionally be 

 observed, in addition to the two marginal ones ; 

 and the depth of the depression from the plane of 

 the marginal ribs is much greater in some than in 

 others. The nearest alliance in form to this spi- 

 culum appears to be that of the tridentate fim- 

 briated equi-anchorate represented by Fig. 150. 

 Plate XXXVII. 



153. CYLINDRO-CRUCIFORM. X 175 linear. From Hya- 



154. lonema mirabilis, Gray, British Museum. The 



155. four forms indicated by the above numbers occur 



156. abundantly on the membranes immediately sur- 

 rounding the thick coriaceous sheath which envelops 

 the spiral column that is projected from the base of 

 the sponge through its centre. All the imaginable 

 varieties of form between Figs. 153 and 156 are 

 found mixed together; and they appear to be 

 especially abundant around that part of the column 

 which is imbedded in the midst of the sponge. 

 The cylindrical form represented by Fig. 153, is of 



