98 
B. NATURAL HISTORY. 
tural, and ought to be homologized with that of Gystiphyllum , or 
perhaps more properly with the vesicular zone of Gyathophyllum and 
Heliophyllum. McCoy has also viewed this vesicular tissue as inter¬ 
cellular, in ranging Stromatopora by the side of Fistulipora. But it 
differs from Fistulipora and Palceopora as well as the Milleporidce in 
general, in the absence of the mural system and the confluence of the 
diaphragms of contiguous individuals. 
It is true that the great predominance of the septal system is capable 
of suggesting very strongly a subordination to the type of Zoantharia 
tabulata; but the want of a mural system shows a divergence equally 
great, and a corresponding affinity with the Aporosa, and exceptional 
cases of the Rugosa with which I associate them; while the general 
affinities of the species which I have discussed throw a great weight 
of evidence in support of their Cyathophylloid relationship. 
It is evident that the different species of Stromatopora which have 
been brought under discussion present three distinguishable plans of 
detailed structure: — 
1. We have the csespitose, completely individualized form, retaining 
traces of lamellae. This is evidently most nearly related to Gyatho- 
pliyllidce ; and I am not aware that it has been noticed by any author. 
2. The forms with the confluent but not obliterated individualities, 
preserving the diaphragms, but losing the lamellae, represented by S. 
polymorpha, Goldf., Sparsispongia, D’Orb. The name proposed by 
D’Orbigny could be retained for this type, if it were not a clear mis¬ 
nomer. 
3. The forms with confluent and obliterated individualities. These 
embrace the original type of the genus Stromatopora. 
The forms described under the name Caunopora, Phillips (Pal. 
Foss. t. x.; fig. 29, etc.), notwithstanding McCoy’s suggestion, seem to be 
sufficiently distinct from Sparsispongia, and should probably constitute 
a fourth generic type holding position next above Stromatopora 
proper. 
If the views presented above prove to be tenable, we shall have 
the following arrangement and diagnoses of Stromatoporidce: — 
Family Stromatoporidce. — Polyps isolated or confluent; exserted, 
never forming a cup; secreting a corallum which consists of a series 
of concentric layers (or diaphragms) of vesicular tissue, separated 
and perforated by vermicular, ramifying passages, which are either 
