MERRILL: FOSSIL SPONGE SPICULES. LT 
Figure 19.  Hymeraphia! sp. Outline perfect. Body egg-shaped, 
and saccular. Spines irregularly arranged on body, short and perhaps 
divided at tip. Size: 0.042 mm. by 0.037 mm.; length of spine, 
0.0057 mm. Somewhat similar forms are figured by Carter as belonging 
to the recent genus Hymeraphia.! It is therefore placed provisionally 
in this genus. 
Figure 20. Geodia? spinipansata, n. sp. | Outline perfect. Body 
egg-shaped and ornamented in a most peculiar way. The significance 
of the two apparent openings on top is not understood. Spines irreg- 
ular in length and size, and variously divided at the terminations. Size : 
diameter, 0.092 mm.; average length of spine, 0.0307 mm. This pecu- 
liar form was not found figured, but from its spiny form I placed it with 
Geodia, and suggest the specific name spinipynsata. 
Figure 21. Geodia? Hilli, n. sp. Spicule perfect. Body elongated 
and smooth between bases of spines. Spines few and irregularly placed, 
spreading at base, tapering rapidly at first, then more slowly to the top 
from which extend three to five short barbs. The hollow tube may be 
seen the whole length of the spine. Size: 0.0938 mm, by 0.0884 mm. ; 
length of spine, 0.0307 mm, This species is one of transcendent beauty. 
Nothing similar has been found figured. It perhaps belongs to some 
genus allied to Geodia, and I propose the specific name Hilli. 
Figures 24, 25, 26, and 30 are very small globo-stellates covered thickly 
with small straight.short spines. They vary in size from 0.023 mm. 
by 0.021 mm. to 0.028 mm. by 0.015 mm. Similar figures have been 
figured by Carter,? in describing the recent form Hymeraphia spiniglobata. 
Figure 27. Small, circular, flat silicious disks with a smooth surface 
and often a dark somewhat irregularly shaped mass in or near the centre. 
Some of these having a dark spot in centre appear to have been replaced 
by amorphous silica, and the dark spot may be a collection of organic 
residue, though Sollas found that a dark spot in the middle of a recent 
sponge spicule was an air bubble. This form is very common, and often 
a hundred or more are found piled upon each other like piles of coin. 
Some of them are solid, but the greater number have a ring around the 
centre, or a black spot filling the centre. They also vary greatly in size ; 
the ones figured are an average ; diameter, 0.05 mm. 
Figure 28. Dermal spicules? Rhomboidal and apparently flat in 
shape. Surfaces often pitted. Average size, 0.021 mm. by 0.0307 mm. 
Not found figured. 
1 Ann. Mag. Nat. Hist., Ser. 5, 1879, Vol. III. Plate XXVI. 
2 Ibid., Vol. IIL, p. 301, Pl. XXVI. Figs. 5-16. 
VOL. XXVIII. — NO. 1. 2 
