dredged ujp from the Gulf of Manaar. 131 



it presents itself much less plentifully ; but, from its much 

 larger size, the less number of its rays and their greater 

 length, together with their irregular disposition around the 

 centre, it is for the most part easily distinguished from the 

 smaller ones, although they may also be, in greater or less 

 number, present in the neighbourhood ; still it seems to me 

 to be but an enlargement of the latter. 



6. " Dermal acerate" or "acuate." In addition to the dermal 

 stellate there is frequently a minute linear spicule on the 

 surface, which may be acerate or acuate in form according to 

 the species, and whose use, as it projects beyond the dermal 

 sarcode, may be, as in other instances, through elevation and 

 depression, to exert some influence over the functions of the 

 pore. 



Geodia jierarmata, Bk. (PI. VI. figs. 32, a-d, 

 33, a-f 34, a-c, and 35, a-d.) 



General form spheroidal. Colour grey. Surface uni- 

 formly wrinkled (now dry) and cribriform (PL VI. fig. 32). 

 Pores minute and numerous in the dermal sarcode, giving 

 to the surface its cribriform structure (fig. 34). Vents small, 

 scattered singly or grouped here and there. Spicules of 

 seven forms, viz. : — 1, the zbne-spicule, whose head consists 

 of three arms, each of which is furcated, and all expanded at 

 right angles to the shaft after the division of the arms, which 

 at first are slightly inclined forwards, shaft 280 by 6-1800ths, 

 head 50-1800ths in diameter (figs. 33, «, and 34, a) j 2, body- 

 spicule, smooth, fusiform, acerate, curved, 200 by 4-1800ths 

 (fig. 33, b) ; 3 and 4, fork and anchor, arms or prongs respec- 

 tively about 5-1800ths long (fig. 33, c) ; 5, siliceous globule, 

 7-1800ths in diameter (fig. 33, d) ; 6 and 7, external and 

 internal stellates respectively, the former 2-6000ths and the 

 latter 6-6000ths in diameter, the rays in both radiating from 

 a small body or central nucleus (fig. 33, e,f). Zone-spicules 

 projecting beyond the petrous crust (fig. 35, c, d), and so 

 supporting the dermal sarcode charged with its stellates 

 (fig. 35, a) as to leave an interval of l-30th inch between 

 it and the former, thus traversed by the shafts of the zone- 

 spicules (fig. 35, Z>, d, and 32, a-c). Petrous crust l-60th 

 thick (fig. 32, c). The other spicules arranged as before 

 mentioned. Size of largest specimen 1 inch in diameter. 



Hob. Marine. Free or attached to hard objects. 



Log. Gulf of Manaar. 



Obs. The distance between the dermal layer and the petrous 

 crust in this species is both remarkable and instructive. It 

 is remarkable because it is so unusual — and instructive be- 



