BY E. F. HALLMANN. 441 



Ptilocaulis rujidns. But there is perhaps equal justification for 

 the view expressed by Tlnele(39), that this species sliould be 

 included in the «;enus Pkycopsis; and it is quite likely that I*hy- 

 copsis and Axiamon are closely allied. 



AxiAMON FOLIUM, sp.nov. (PI. xviii., figs. 2, 3; PI. xxiv., figs 7, 8; 

 and text-fig.23). 



1902. Reniochalina stalagmifes{cvv.) + Reniochalina la7neUa{eri\), 

 Whitelegge(56), p.283. 



Two specimens only are at hand - those which Whitelegge 

 very briefly and not quite accurately described as the types 

 respectively of Reniochalina stalagmites and Reniochalina lamella; 

 and as these differ to some extent in certain external features, 

 and may thus be varietally distinct, it is advisable to mention 

 that I choose, as the typical specimen, that which Whitelegge 

 took to be R. stalagmites. 



Description. — Hponge flabellate, stipitate; the lamina entire, or 

 palmato-digitate, or deeply dissected into branch-like parts. 

 Surface ornamented with longitudinal close-set septiform ridges, 

 usually either deeply notched at short intervals or segmented 

 into separate languettes; between the ridges, the lamina is ex- 

 ceedingly thin except in the rt!gion of the stalk. Consistency in 

 the dry state, dense, hard, tough, fiexible within limits; colour 

 greyish-brown. 



The digitate typical specimen (PL xviii., fig. 2), which is incom- 

 plete below, measures 250 mm. in height, and is provided with 

 highly segmented ridges averaging 3 mm. in height, and set at a 

 distance apart of irom 2 to 3 mm. The second specimen (PI. 

 xviii., fig. 3), 145 mm. in height, has continuous though deeply 

 crenate ridges, averaging 1*5 mm. in height and 1 to 2 mm. in 

 distance apart. 



The main skeleton is a compact lattice-like reticulation with, 

 for the most part, rhomboidal meshes, composed of spongin- 

 ensheathed spicules arranged (somewhat confusedly) in pauci- 

 serial fibres; the sides of the meshes are of about a spicule's 

 length. Better defined primary fibres are sometimes observable 

 running longitudinally and gradually trending outwartls; but, as 



