PLATE V. 



Psammophyllum. 

 Figs. 1-4. Psammophyllum reticulatum, n. sp. (p. 50). 



Diam. 



Fig. 1. A young specimen. The entire parenchyma of the flabelliform sponge 

 is traversed by a coarse network of brown cylindrical tubes, the 

 hydrorhiza of a symbiotic Hydroid (Stylactella ?). The meshes of 

 this coarse network are filled up by a very fine and delicate network, 

 composed of branching and anastomosing spongin-fibrillae, which 

 enclose and connect foreign bodies, mainly siliceous spicules of 

 different sponges, . . . . . . x 10 



Fig. 2. A small portion of the skeleton of the flabelliform sponge. Between 

 the thick brown tubes of the symbiotic Hydroid (h), the fine net- 

 work of the yellow spongin-fibrilke (f), and numerous scattered 

 xenophya (x) are visible, . . . . . x 100 



Fig. 3. A small portion of the same ; less highly magnified. Characters as in 



fig. 2, . . . . . . . x 50 



Fig. 4. A few xenophya (sponge spicules and Radiolarian fragments) cemented 



together by the scanty j^ellow spongin-fibres ( /*), . . . x 300 



Fig. 5. P sammopliyllum flustraceum, n. sp. (p. 51.) 



Fig. 5. A forked chitinous tube of a symbiotic Hydroid (h) ; the epithelium 

 on its inside is exceptionally well preserved. In the surrounding 

 maltha of the sponge are visible single amoeboid cells and eggs (e), 

 and between them are scattered a few xenophya (x), and the con- 

 necting yellow spongin-fibres, . . . . x 200 



