792 NEW GENERA OF MONAXONID SPONGES, 



DESCRIPTION OF PLATES XXXVI.— XL. 



Plate xxxvi. 



Fig.l. — Moderately thin transverse section of a branch of Tenaciella 

 canaliculata Whitelegge. The very dense peripheral layer is 

 formed by the dermal skeleton and the sabdermal brushes. 

 The central region of the skeleton is relatively sparse and not 

 displayed to advantage ; but the intermediate zone between 

 it and the peripheral layer, consisting of the radial fibres, is 

 well shown, (x 12^). 



Fig. 2. — Longitudinal section of the main skeleton of a branch of Ten- 

 aciella canaliculata Whitelegge. (x 15). 

 Plate xxxvii. 



Fig.l. — Entire specimen of Tenaciella canaliculata Whitelegge. 



Fig. 2. — Longitudinal section of the skeleton, in proximity to the tip of 

 a branch, of Axociella cylindrica Ridley and Dendy . (x 12^) . 



Fig. 3. — Longitudinal section of the skeleton !of an older portion of a 

 branch of Axociella cylindrica Ridley and Dendy. (x 12J). 



Fig. 4. — Portion of a specimen of Axociella cylindrica Ridley and 

 Dendy. 



Plate xxxviii. 



Entire specimen of Ophlitaspongia Ihetidis sp. nov. 



Plate xxxix. 



Fig.l.- — Portion of a section of the skeleton of Isociella jiabellata Rid- 

 ley and Dendy, taken from near the outer margin of the 

 sponge — the plane of section being approximately parallel to 

 the mid-plane of the sponge-lamina, (x 12£). 



Fig. 2. — Portion of a longitudinal section of the skeleton of Isociella 

 Jiabellata Ridley and Dendy, taken at some distance from 

 the margin of the sponge — the plane of section being per- 

 pendicular to the mid-plane of the sponge. The stouter 

 fibres appearing in this section are exceptional ; they are 

 "veinlets" which here and there proceed off from the stout 

 "veins" shown in PL xl. , fig.l. (x 12J). 



Plate xl. 



Fig.l. — Portion of a longitudinal mid-plane section of the skeleton of 

 Isociella Jiabellata Ridley and Dendy, taken from an older 

 portion of the sponge at some~short distance above the stem ; 

 showing the stout ramifying "veins" or "funes.",-- (Owing 

 to the extreme fragility of the skeleton the section is not in- 

 tact), (x 5). 



Fig. 2. — Longitudinal section of the skeleton of a branch cf Ophlita- 

 spongia ihetidis, sp. nov. (x 12^). 



