{29 Mr. H. M. Bernard on the 
have travelled. Hence, although one would never have 
selected a tissue like the coenenchyma, which all experience 
shows to be dangerously variable, as a basis for classification, 
there is in the present case really no choice, 7. e. if our mor- 
phological diagnosis is correct. Hitherto the variations of 
the surface coenenchyma—very superficially handled—have 
been accorded only a secondary place. Dana, deducing Monti- 
pora (Manopora) from Madrepora by the degeneration of the 
calicles, classified its species accordingly into those in which the 
protuberant calicles persisted and those in which they had 
quite disappeared, the latter group being further subdivided 
according to the form of the corallum and the character of 
the surface. Milne-Edwards and Haime divided the Monti- 
pore primarily according to the form of the corallum. We may 
at once dismiss this latter classification as purely artificial. 
Returning, however, to Dana, it must be noted that there 
is no evidence whatever to make us believe that Monti- 
pora is deducible from Madrepora by gradual degeneration of 
protuberant calicles. The only Montiporan forms which 
Dana adduced as transitional hardly support his contention : 
one—M. gemmulata—has been removed by Verrill to the 
Turbinarians, while the protuberant calicles in the other— 
M. caliculata—are not true calicles in Dana’s sense, but a 
peculiar specialization of the interstitial coenenchyma which 
will be referred to again. 
We have, then, no choice but to accept the variations in 
that tissue, the specializations of which are essentially the 
peculiarity of the genus, as the basis of classification. Be- 
neath all its baffling superficial variations the laws of its 
growth can be made out and the main lines along which 
it has diverged can be traced. ‘This serves to divide the 
genus into groups which have some claim to be natural. 
Uncertainty, however, comes in when, in further subdividing 
these groups, we come within range of the superficial varia- 
bility due to accidents of position and nutrition. It must 
therefore be at once confessed that many of the assumed 
specific variations are not to be relied upon. The “ species” 
established are in many cases only descriptions of individual 
specimens the surface characters of which give no clue as to 
their affinities with other specimens. Of course in many 
cases there are other characters sufficiently striking to justify 
us in confidently claiming new and distinct types. 
The following analysis of the development of the ccenen- 
chyma was only very gradually arrived at after studying 
series of sections revealed by fractured specimens. It will be 
best understood if we reverse the process of its discovery, 
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