126 Mr. H. M. Bernard on the 
become stout solid trabecula. The rest of the reticulum 
merely forms the cross pieces which support these trabecule. 
Every stage in the gradual differentiation of these trabeculae 
can be traced. In many cases the more vertical elements of 
the thickening reticulum run in nearly straight lines, but 
without thickening. Comparison of specimens shows that 
the thickening was due to the rising up of the tips of these 
vertical threads above the surface, perhaps at first as echinule. 
These became stouter and stronger, probably for protective 
purposes, and thus, as they sank beneath the rising surface, 
became thick trabecule (fig. 3c). 
This group, showing the rising of stout trabecule above 
the surface to form protective “ tubercles,” is very large and 
contains more than forty types. The distribution and shapes 
of the tubercles are very varied: they may be densely 
crowded as minute rounded granules or tall and lancet- 
shaped; they may be grouped in rings round calicles, or, 
again, they may run together to form thin keels or ridges. 
This group is called the “ tubereulate ” group. 
We thus have four main divisions of the genus—glabrous, 
foveolate, papillate, and tuberculate—each term having refer- 
ence solely to a peculiar specialization of the coenenchyma. 
While the first three of these terms need no comment, the 
last requires justification. 
In all the earlier descriptions of Montiporan types the terms 
papille and tubercle seem to have been used indiscriminately. 
It is often impossible to tell whether a writer was describing a 
specimen belonging to group 3 or to group 4. The most 
important use of the word tubercle occurs in Lamarck’s 
description of the specimen Porites tuberculosa, Lk. (= Monti- 
pora tuberculosa). In fixing the use of the word tubercles to 
mean the small solid tips of individual trabecule when they 
project above the surface, I have been led to do so by the 
conviction that these were Lamarck’s “ tubercles” as seen on 
his type “ tuberculosa.” Certain expressions in Lamarck’s 
text point clearly to this. In describing P. tuberculosa* he 
speaks of “les tubercules dont la surface est parsemée”’ as 
being “ graniformes ou columniformes ;”’ and, again, on the 
next page he speaks of interstices being “ hérissés de tuber- 
cules.” Both these expressions are quite inapplicable to the 
much larger swollen reticular knobs here called papille. 
One other remark on these tubercles with their trabecula- 
like sunken portions. It was the presence of these trabecule 
which appears to have misled Milne-Edwards. He compared 
* © Animaux sans Vertébres,’ ii. 1816, p. 272. 
