BOTANY AND ZOOLOGY. 
99 
radially or confusedly disposed. Mural system wanting; lamellar 
structure distinctly present only in the higher forms. 
Genus, Idiostroma, (n. g.) — Polypi completely isolated, forming 
branching masses; lamellar system, represented by a radial structure. 
Species, I. caespitosum, gordiaceum. 1 
Genus, Ccenostroma, (n. g.) — Polypi confluent, but individualized, 
forming elongated, or spheroidal, compound masses ; diaphragms com- 
* mon and continuous throughout; lamellar system indicated by the 
radiate arrangement of the vermicular passages which commonly di¬ 
verge from the summits of little eminences raised in the concentric 
laminae. 
Species, C. pustulosum, monticuliferum, granuliferum , 2 3 polymor- 
plium, radiosum, ramosum. 
Genus, Gaunopora 3 (Phillips). — “Corallum polymorphous, com¬ 
posed of minute, irregular, vermicular, cellulose tissue, disposed in 
obscure concentric layers, traversed by few long, larger,, variously dis¬ 
posed, vermiform, cylindrical channels.” (McCoy, Brit. Pal. Foss, 
p. 66.) 
Species, G. placenta, ramosa, verticillata. 
Genus, Stromatopora (Goldf.)—Polypi confluent, with individualities 
sensibly obliterated. Corallum consisting essentially of confluent dia¬ 
phragms, or concentric layers, which generally inclose a foreign .body* 
—being secreted on all sides of it and forming a spheroidal mass. 
Species, S. concentrica, striatella, nux, rugosa, compacta, nummu - 
litisimilis. 
1 Idiostroma gordiaceum (n. sp.) — In general appearance resembles I. ccespitosum. 
The stems, however, are intricately entangled, and radial lamellas have a distinct 
existence ; thus showing a still nearer approach to the Cyathophylloids. A very 
interesting species from Iowa City, Iowa. 
2 This species occcurs at Charleston Landing, Indiana, a few miles above Jef¬ 
fersonville. It differs from C. pustulifera in having the upper surface of the layers 
more minutely pustuliferous or granulated. 
3 It is yet desirable to compare authentic specimens of this type with specimens 
of Idiostroma ; though, if, as McCoy asserts, its affinities are with Sparsispongia 
(from which I think it differs materially), it is a very different type from Idio¬ 
stroma. 
