MERRILL: FOSSIL SPONGE SPICULES. 15 
apparently, communication of the centre with the outside. As has been 
mentioned, these spicules have not been replaced, but are most likely 
still in the original colloidal condition. Тһе bright transparent yellow 
color is perhaps due to à change brought about bythe action of some 
organic acid which may be a beginning of the replacement process. 
When viewed with high power lens, these bright yellow spicules, radiating 
in perfect symmetry from the hollow centre, are exceedingly beautiful, 
and in their various forms present a contrast both novel and interesting. 
These all belong to the family Geodide, Lamarck, and with one or two 
exceptions none of them have been figured as fossil, but most of them 
are similar to the recent forms referred to in the description. In the 
Fossil Sponges of Upper Chalk, Dr. Hinde figures a globo-stellate spicule, 
body ornate and covered with short sharp spines. This is, however, 
much larger than the spicules of the Texas flint. Professor Zittel also 
figures two globo-stellates, somewhat similar in form to Figure 16 of the 
Texas flints.! They are much larger, however, and none have been 
found with barbs on the ends of the spines. This may be due to the 
fact of imperfect preservation, but it would seem from the number of 
specimens examined some indication at least of barbs would have been 
detected if present. 
In Oscar Schmidt’s * Die Spongien des Atlantischen Gebietes ” noth- 
ing is given similar to the globo-stellates of the Texas flints. In his 
“Sponges of the Adriatic Sea,” however, he figures globo-stellates of Geo- 
dia placenta.? These have spherical bodies with round straight spines, 
but they are much larger. The measurements given were taken from 
tip to tip of spines at right angles to each other, and then the length of 
& spine is given. 
These spicules doubtless belong to genus Geodia or some allied genus, 
as Tethya or Stellata. The body is somewhat globular and the spines 
rest squarely on bases more or less enlarged. 
Figure 13. Geodia? spini-curvata, n. вр. Imperfect, elliptical, sphe- 
roidal, ornamented with what might with higher power lens prove to be 
minute blunt spines. Body has also long spines, smooth, slightly curved 
and irregularly arranged. Size: 0.096 mm. by 0.065 mm.; length of 
spine, 0.035 mm, Nothing similar to this has been found figured. From 
the slight curve of the spines I propose the specific name spint-curvata. 
Figure 12. Geodia? cretacea, n. sp. Perfect. Much like Figure 13. 
Body ornate, smooth, and bearing numerous long and slightly curved 
1 Abh. K. Bayer. Akad, Wiss. d. Mün., XIL, Bd. IIL, Taf. V. Figs. 27 and 30. 
? Die Spongien des Adriatischen Meeres, p. 49, Taf. IV. Fig. 7a. 
