66 BRITISH PALAOZOIC FOSSILS. [Zoopuyra. 
Subgenus. Caunopora (Phill.) 
= Sparsispongia (dVOrb.) 
Gen. Char.—Corallum polymorphous, composed of minute irregular vermicular cellulose tissue, disposed 
in obscure concentric layers, traversed by few long, larger, variously disposed, vermiform, cylindrical channels. 
From what I have stated of the small vertical channels in the typical species of Stromatopora, it is 
obyious that there is no structural difference between these genera, beyond the irregular porosity of the 
tissues in Cawnopora, and the more regular concentric lamination of Stromatopora. It is impossible on any 
account to separate generically the Stromatopora polymorpha, forming the type of d’Orbigny’s genus Spar- 
sispongia from the Caunopora placenta; the star-like convergence near the surface of certain sets of the 
vertical channels being merely a specific peculiarity, interspersed in the intermediate spaces with the ordinary 
straight tubuli. 
——— 
f ly WU YM YY 
a_Stromatopora (Caunopora) verticillata (MeCoy) two branches, natural size, each shewing the surface near one end, and 
a section in the rest of the length shewing the central canal and whorls of verticillate tubuli. 6 Portion of surface and hori- 
zontal and vertical sections of ditto, magnified. c Petraia Gigas (MeCoy) natural size. d Worn section of apex, natural 
pe stewing, the solid filling up of the young cavity and cause of the obtuse apex to the cast. e Natural section of ditto, 
natural size. 
STROMATOPORA (Caunopora) PLACENTA (Lonsd. Sp.) 
Ref. and Syn.—Coscinopora placenta Lonsd. Geol, Trans. Vol. V. t. 58. f. 5. (not of Gold.) Cawnopora 
placenta (Phill.) Pal. Foss. t. 10. f. 29. 
Sp. Ch.—Corallum forming amorphous masses, composed of thin obscurely defined, concentric layers, 
traversed by long cylindrical nearly vertical, subparallel, vermiform, thick-walled tubes, one-fourth to one- 
third of a line in diameter, averaging a line apart ; intervening tissue minutely reticular, composed of small 
thick vermicular vesicular plates. 
The longitudinal persistent channels of this species have distinct calcareous walls, rendering them un- 
usually conspicuous in the vertical section or fracture. The Coscinopora placenta of Goldfuss, to which the 
present species has been referred by Lonsdale and Phillips, has the tubes so very much larger, and fewer 
in a given space, that their specific identity is impossible, and it has been referred by d’Orbigny (from 
specimens in his cabinet) to his genus Geoporites (Palwopora), in which the tubes have transverse dia- 
