dredged up from the Gulf of Manaar. 149 



manner, 3-6000ths of an inch long (fig. 50,/), — the former 

 plentifully distributed over the disks, as before mentioned, 

 and but little less so throughout the rest of the structure, 

 while the latter sparsely accompanies it. Size of largest 

 specimen about | inch in horizontal diameter, and the thick- 

 ness of the depression on the nodule where it may have grown, 

 often extending into the cavities formed by excavating 

 sponges. 



Hab. Marine. On hard objects. 



Loc. Gulf of Manaar. 



Obs. The remarkably shreddy character of the advanced 

 form of disk (fig. 50, i) and the presence of the spinispirular 

 flesh-spicule, together with the comparatively large size of its 

 companion the acerate flesh-spicule, distinctly separate this 

 from the other species of Discodermia. It may be remem- 

 bered that the flesh-spicule of Dactylocalyx Masoni, Bk., is a 

 spinispirula (Proc. Zool. Soc. 1869, pi. vi. fig. 4). 



Discodermia ladvidiscus, n. sp. 

 (PI. VIII. fig. 51, a-i.) 



Surface even, discophorous, disks horizontal, structure areo- 

 lar, accompanied by an acerate flesh-spicule (PI. VIII. fig. 51). 

 Colour yellow internally. The disks here, which also present 

 a great number of faint lines, like those of the foregoing species, 

 are depressed in the centre (fig. 51, b, c). They undergo 

 similar transformation to those of the foregoing species 

 (fig. 51, e), passing at last into the fully formed spicule of the 

 interior (fig. 51, hk), whose terminations appear to be more 

 in expanded, irregular surfaces, for the sake of union by apposi- 

 tion with their neighbours, than in filigree processes interlocking 

 (fig. 51, *). Flesh-spicule acerate, curved, fusiform, micro- 

 spined, about 8-6000ths long (fig. 51, f g), plentifully dis- 

 tributed over the disks (fig. 51, a) and throughout the 

 interior, as in the foregoing species. Size of specimen about 



5 inch in horizontal diameter. 



Hab. Marine. On hard objects. 



Loc. Gulf of Manaar. 



Obs. When viewed in situ (fig. 51) the depressions in the 

 centres of the disks, which are rather less in diameter 

 than those of the other species, together with the concen- 

 tric lines, added to the comparative absence of filigree ter- 

 minations in the fully formed spicule, and the yellow colour 

 of the interior, are sufficient to distinguish it from the other 

 species ; while the absence of papillae on the disks causes it to 



Ann. & Mag. N. Hist. Ser. 5. Vol. vi. 11 



