310 1VI. K. A. Zittel on Fossil Tetractinellidce. 
Geodites , Stellettites , Dercites , and Monilites are also repre¬ 
sented. 
Numerous anchors and spicules belonging to Geodia and 
Donatina also occur in the tubes met with near Brussels 
in the Eocene sands, which have been described by Car¬ 
ter * * * § under the name of Broeckia. The sponge-spicules 
themselves were first carefully investigated and figured b) 
Rutotf. 
Under the denomination Esperites giganteus , Carter J men¬ 
tioned a sigmoidally curved uniaxial form of spicule of con¬ 
siderable size from the Greensand of Haldon. Similar spicules 
were subsequently described by Rutot (l. c. pi. iii. figs. 5 
and 29) from the Eocene sands of Brussels, and by myself 
(Abhandl. k. bayer. Akad. 2te Cl. Bd. xii. pi. iv. figs. 25, 26) 
from the Upper Cretaceous of Westphalia. I have also re¬ 
peatedly found them in the residue left after treating Upper 
Jurassic sponges with acid. When Carter § had observed 
spicules of exactly concordant size and form in a collection 
of living deep-sea sponges associated with three-pointed an¬ 
chors, he considered that they must be referred to the Pa- 
chastrellidae, and proposed for them the name of Ophirhaphi- 
dites. 
The University Museum at Gottingen possesses the some¬ 
what compressed fragment of a siliceous sponge from the 
Quadratus-c\\d\k of Linden, near Hanover, measuring 80 
millims. in length, 16 millims. in breadth at the upper, and 
9 millims. at the lower extremity, and consisting of simple, 
more or less undulated, smooth spicules, which exactly agree 
with those of Ophirhaphidites . The length of these spicules, 
which have unusually wide axial canals, varies between 1^ 
and 5 millims. ; they all lie, closely packed together, in the 
direction of the long axis, are intimately interlaced, and have 
no free space between them for either longitudinal or trans¬ 
verse canals. Among these curved bacillar spicules simple 
quadriradiates occur quite isolatedly, having one arm usually 
much elongated—as a rarity also forked anchors with a long 
shaft and short prongs. I name this remarkable form Ophi¬ 
rhaphidites cretaceus. 
1 have received another interesting Tetraetinellid form 
allied to Tethya from the Quadratus-dimW. of Ahlten, through 
Dr. Steinmann. It forms a distinct genus :— 
* Ann. & Mag. Nat Hist. ser. 4, vol. xix. (1877) p. 382. 
t Ann. Soc. Malac. Belg. vol. is. (1874) pi. iii. 
1 Ann. & Mag. Nat, Hist, ser. 4, vol. vii. (1871) p. 131, pi. 
fig. 79. 
§ Ibid. vol. xviii. (1876) p, 458, 
x. 
