308 
M. K. A. Zittel on Fossil Tetractinellidee. 
Inocerami belong with more certainty to Cliona. They occur 
most abundantly, however, in the Tertiary formation. 
A number of species have been established by Conybeare, 
Michelin, D’Orbigny, and Pomel, partly under the generic 
name of Cliona , partly as Vioa ; but as the skeletal spicules 
have not been detected in any one of these species, no great 
importance can be assigned to them. 
The simple or ramified perforations and passages occurring 
in Belemnites and fossil shells, for which Hagenow * * * § , Quen- 
stedt f, and Etallon J have proposed the genera Talpina, 
Hag., Dendrina , Quenst., Hagenowia and Cobalia, Et., I 
regard as quite problematical. Among living sponges I am 
acquainted with no form that hollows out similar passages ; 
and I am therefore rather inclined to ascribe them to boring 
worms. 
IV. Tetractinellidje, Marshall. 
Siliceous sponges with spicules of the pyramidal type (qua- 
driradiates, octoradiates, anchors). 
The order Tetractinellidse embraces the two families Geodi- 
nidse and Ancorinidse of O. Schmidt, or that part of Carter’s 
Holorhaphidota in which the skeleton is composed of siliceous 
structures based upon the axial cross of a three-sided pyramid. 
These are all the representatives of the family Pachytragida 
and the group Pachastrellina of the family Pachastrellida, to 
which Carter also refers the Lithistidse. 
The most ancient Monactinellid spicules have been described 
by Carter § from the Lower Carboniferous Limestone of Cun- 
ningham-Baidland in Ayrshire. For the first demonstration 
of fossil spicules of the present order we are indebted to the 
same meritorious spongologist. 
As long ago as 1871 Carter || figured among the isolated 
sponge-spicules in the Greensand of Haldon a considerable 
number which, in their form, most closely resemble the an¬ 
chors, quadriradiates, and siliceous spherules of the genera 
Geodia, Pachastrella, Tethya , and Stelletta. Although a part 
of these might be derived from Lithistidse, others certainly 
belong to the Tetractinellidse. Carter describes the fossil 
spicules under the generic names Geodites , Dercites, and Stel- 
lettites , according to their relationships to existing forms, and 
gives a series of figures on plates ix. and x. of his memoir. 
* Jahrb. fur Min., Geol. und Petref. 1840, p. 671. 
t Petrefactenkunde Deutschlands, Cephalop. pi. xxx. figs. 86, 37. 
J Actes de la Soc. Jurass. d’Emul. de Porrentruy, 1860. 
§ Ann. & Mag. Nat. Hist. ser. 5, vol.i. (1878) p. 139. 
|| Ann. & Mag. Nat. Hist. ser. 4, vol. xn. (1871). 
