42 GUIDE TO THE FOSSIL INVEETEBIIATE ANIMALS, 
;Gallery X. 
Wall-case 
8 c. 
Wall-case 
8b. 
Wall-case 
8a, 8b. 
Wall-case 
7b. 
Wall-case 
7A. 
' Wall-case 
7 a, comer. 
Table-case 
16. 
Prom tins island and from Tennessee comes the noteworthy 
Octactinellid, Astraeospoiiffia. 
The Devonian of North America yields casts of Hydno- 
cc?’«s, a Lyssacine Hexactinellid. Part of a large sponge-bed, 
formed oi' this, is shown in a special case. 
From the Triassic strata of St. Cassian there is a series 
of small Calci.spougiae, which have been referred to Stelli- 
sponyia, ConjncUa, and other genera of Plniretrones. 
The Upper Jurassic rocks of Wiirtemburg and Switzer- 
land, known as the White Jura, contain a large number of 
Hexactinellida and Lithistida, some layers lieing mainly 
composed of these si^onges. They retain their outer form, 
but, in nearly all, the siliceous skeleton has been replaced I. 15 ' 
calcite. Examples of numerous genera are exhibited. 
Among the Cretaceous sponges, special notice should be 
taken of the fine specimens of Goeloptyclmim, from the 
Westphalian Upper Chalk, and of the exrpd.site series of 
Hexactinellida and Tetractinellida from the Upper Senonian 
Chalk of Hanover prepared by Dr. A. Schrammen by carefully 
dissolving out the siliceous skeleton from the calcareous rock : 
alone among fossil sponges do these present the beauty so 
frequent in the skeletons of recent forms. Those illustrated 
in the accompanying Plate 111 are : (1) Calyptrdla tenuis- 
sivia ; (2) a species of llliiz(ypoterion ; (3) Sp)oradoscinia 
Dechcni, the upper figure showing the interior with the 
canals, into which open the ostia seen in the lower figure ; 
(4) Aphrocallistes alveolites. 
Tertiary sponges are so rare that one must not overlook 
the Calcispongiae, Tretoenlix, Bactronella, and IHcctroninia, 
which are modified Pharetrones from the Eocene of Australia. 
The Trustees issued in 1883 a Catalogue of the Fossil 
Sponges in the Museum l)y G. J. Hinde, who has also begun 
a Monogi'aph of the British Fossil Sponges, published by the 
Palaeontogj'aphical Society (1887, 1888, 1893). See further 
E. A. Minchin, Section on Sponges in Lankester’s “ Treatise 
on Zoology,” London, 1900. 
The Archaeocyathinae are a peculiar group of organisms 
found in the oldest fossil-bearing rocks in many parts ol the 
world. Their calcareous skeletons, which built up vast 
reef-like masses, remind one in some respects ol sponges, in 
other respects of corals. They have also been compared to 
Algae. Probably they were of animal nature, and independ- 
ently descended from the I’rotozoa. 
