On a Badiolarian, &c. By Prof. P. Martin Duncan. 179 



regular hexradiate spicule, a form which is very abundant in 

 Hyalonema. In the youngest sponges, the stellate arrangement of 

 the outer membrane is not yet perceptible ; the surface is merely 

 divided by the spreading rays of single spicules into rudely square 

 meshes. The osculum is distinct from the first. 



" The feathered spicules are seen along the shafts and branches 

 of the spicules of the outer and oscular walls. All have a beard of 

 a single pencil of long spicules passing out through one of the 

 meshes of the outer wall, in the centre of the narrow inferior end of 

 the sponge, opposite the crown of the osculum. The fascicle con- 

 sists of from twenty to thirty of the long, simple spiculae. and four 

 or five of the bihamate spined spicules. At this stage, it is diffi- 

 cult to distinguish young Holtenise from young Syalonemge." 



Other small HoUenim have been described by Oscar Schmidt ; * 

 one, Roltenia Pourtalesi Schmidt, from Florida, 154-324 fathoms, 

 and Holtenia saccus Schmidt, from the same locality. Both are 

 without the pencil of long, axial, glossy spicules, but have a toler- 

 ably wide oscular opening, and their spiculse differ from those of the 

 new form. 



The question. Is this microscopic sponge an adult ? is not very 

 readily answered. Were the body less complicated, and less elabo- 

 rately stellate, there would be no difficulty in replying that it is not, 

 but it is a perfect little sponge in all its parts. As there is some 

 uncertainty about the stage of growth which the sponge presents, 

 although it is advanced far beyond the gemmule stage, I do not 

 propose to associate it with any genus or species, but simply to 

 record it as a minute, highly- developed Hexactinellid of the Lyssa- 

 kine division. 



(Description of the illustrations of the Lyssatine Hexacti- 

 nellid : — 



Fig. 7. The sponge, magnified 50 times. 

 „ 8. The primary spicule, magnified. 

 „ 9. The feathered spicule, magnified. 

 „ 10. Small hexactinellid spiculae, magnified.) 



* 'Grundziige einer Spong-fauna des Atlan.-Gebietes,' Leipzig, 1870, pp. 14, 15. 



