888 The American Geologist. n.cemhor, i897 
both without iiiid witliiii, to the cj^liiidrieal, chambered, siphon- 
ated sliells of Orthoceras, and, indeed, the first of them to be 
described was termed Orfhoceras vesiculosum by DeKoninck.* 
These sponges have been grouped together by 8teinmann 
nwdev \\\e WiWwv S phi in- tozoa .\ This author has divided all 
the extinct members of the order Calcarea ov Calcispoii gin into 
the tw(t groups, J nozod and Sphinctozoa, and the latter are thus 
defined:]; "Sjihinctozoa. The simple or compound sponge- 
bodies consist of ring-, or ball-shaped segments, 'ijslieir outer 
wall is penetrated by simple, and for the most jiart, straight 
canals, or is quite solid." 
In contradistinction to these tiie I iiozou are defined as thick, 
massive and compound, and penetrated by branching canals. 
Among later writers, Rautf,§ and, following him. Zittel, |[ 
regard the most of these Sphinctozoci as related to the existing 
calcisponge Sycoti, on account of the simi)le character of the 
radial canals and have hence assigned them to Hai^ckel's or- 
der Sycone.s. It has been clear to all students of these fossils 
and is very evident in the specimens now under considei'ation, 
that skeletal spicules are of great rarity or seldom distin- 
guishable, the walls being a compact, calcareous mass with 
coarse perforations and often a distinctly fibrous structure. 
Steinmann laid little importance upon the existence of a 
coarse, vesicular structure in these Sphinctozoa, possibly be- 
cause it was not clearly exhibited by his specimens, but in 
those described by Waagen and Wentzel, from the middle Pro- 
ductus-limestone of India, ^ as well as the Nebraska specimens, 
this vesicular structure is very pronounced, the vesicles 
being produced by laminar diaphragms arching from one wall 
*Qu.irt. Jour. Geol. See, London, xix, p. 15. 
fCi. Steinmann; Phh,retronen-studien (Neues Jahrb. fiir Mineral., 
1882, 2, pp. 1.39-191, pis. 6-9). Both here and elsewhere Steinmann has 
regarded these bodies as Pharetrones (see also Steinmann and Doeder- 
lein, Elemente der Palseontologie, pp. 70-7.3, 1890), employing this term 
in, perhaps, a somewhat broader sense than did Zittel in erecting it into 
ordinal value. 
JPalseontologie, at cit., p. 71. 
ijPalajospongiologie, 1st Th., pp. 100-102, 189.3. 
IIGrundziige der Palseontologie, p. Gl, 1895: and Eastman's Zittel's 
Text-book ot" Palaeontology p. 65, 1896. 
][See Memoirs, Geol. Surv. India: Palaeontologia Indica, Ser. xiii, Salt 
Range Fossils, 1, Productus-limestone, 7, pp. 907. et seq., pis. 102-104. 
1887. 
