M. K. A. Zittel on Fossil Tetractinellidas. 
309 
A group of fossil bacillar spicules, quadriradiates, and anchors 
with annular constrictions, as yet only known in the fossil 
state, are embraced under the name of Monilites ( l. c. pi. ix. 
figs. 44-47), and constitute an exceedingly characteristic ex¬ 
tinct type. I have detected isolated spicules of the same 
form in the North-German Cretaceous of Ahlten; and they 
are also mentioned by Rutot from the Eocene sands of 
Brussels. 
In my monograph of the genus Coeloptychium I have like¬ 
wise figured a great number of isolated siliceous structures, 
which I at that time erroneously referred to Coeloptychium. 
The radiate siliceous spherules and disks (?. c. pi. v. figs. 18- 
26) are probably derived from fossil species of Stelletta or 
Geodia• the spinous spherules (l. c. pi. v. figs. 27-30) pro¬ 
bably belong to Pachastrella or Geodia, and the radiate stars 
(fig. 31) to Tethya , CaHites, or Pachastrella. How many of 
the four-, seven-, and eight-rayed stars and anchors figured on 
pis. v., vi., and vii., as also of the uniaxial spicules repre¬ 
sented on pis. iv. and v., are derived from Pachytragidse, Pa- 
chastrellicla3, Lithistidm, or other groups of sponges, it is im¬ 
possible to decide, owing to the indifferent character of these 
structures. I believe, however, that I must now definitely 
refer the dense, non-radiate, ovate bodies (pi. iv. figs. 52-59), 
as also the spherules ( l . c. fig. 66), to the Geodice, as I have 
found precisely concordant bodies in the Upper Jura in great 
quantities lining a cavity in which numerous forked anchors 
and quadriradiates were scattered. Similar elliptical, oval, 
and spherical bodies occur very abundantly in the White Jura, 
associated with bacillar spicules and anchors. 
The existence of Tetractinellicke may also be recognized in 
the Lias and Rlimtic. I have received, through Mr. Nelson 
Dale, from the Upper Lias of the valley of Conzei near Pieve 
di Ledro, in South Tyrol, a piece of rock about 70 millims. 
long and 35 millims. thick, which entirely consists of large 
siliceous spicules. A tenth part of these are simple, pointed 
at both ends, and about 4-5 millims. in length. Among 
them are isolated large quadriradiates (cross-spikes). 
Precisely similar straight or slightly curved bacillar spicules, 
intermixed with forked anchors and fragments of Hexactinel- 
lidas, form a deposit several centims. thick, in the horizon of 
Avicula contorta, on the Hochfell, in the Bavarian Alps. 
The occurrences in the Greensand of Haldon are most in 
accordance with the sponge-spicules described by Joseph 
Wright* from the Irish Cretaceous, among which the genera 
* Report Belfast Nat. Field Club, 1873-74, Appendix. 
Ann. cfc May. N. Hist. Ser. 5. Vol. iii. 21 
