AMONGST THE CORALS OF THE PALAOZOIC PERIOD. 245 
b. In the second place, there are not a few instances in which the mode of 
increase differs widely in individuals even of the same species. Thus, in Helio- 
phyllum Hall, Edw. and H., the ordinary individuals are truly simple and do 
not produce any buds at all; other individuals exhibit simple calicular gemma- 
tion, and form a vertical succession of cups produced singly and successively 
in the same longitudinal axis; other examples exhibit a modification of com- 
pound calicular gemmation, in which the aged corallum throws up a tuft of 
small and abortive corallites from its calicine surface, whilst a few individuals 
show the ordinary and typical form of compound calicular budding. In Cyatho- 
phyllum ceespitosum, Goldfuss, again, the mode of growth is typically by calicular 
and lateral gemmation combined with one another; but other examples of the 
species are stated by D’Orzsicny, M‘Coy, and Mitne-Epwarps, and HaIME to 
increase by fission. Finally, there are numerous instances in which the form 
of the corallum, within the limits of the same species, becomes very mutable in 
consequence of variations in the mode of growth. Thus, the same species may 
be at one time fasciculate, and at another time astreiform, or at one time 
massive, and at another time ramose. 
c. In the third place, the small classificatory value of the mode of growth of 
the corallum, comparatively speaking, is strongly shown by the marked and 
striking variations in this particular exhibited by closely allied species of the 
same genus. Very many examples of this could readily be brought forward, 
but a few will be sufficient. In the genus Cystiphyllum, for example, we find 
species such as C. vesiculosum, Goldfuss, C. Americanum, Edw. and H., C. 
grande, Billings, C. mundulum, Hall, C. Ohioense, Nich., C. cylindricum, Lons- 
dale, C. Grayi, Edw. and H., C. Senecaense, Billings, C. Siluriense, Lonsdale, 
and C. sguamosum, Nich., in which the corallum is either invariably simple, or 
at most produces a few buds by a process of simple calicular gemmation. In 
Cystiphyllum fruticosum, Nich., however, we find a truly compound corallum, 
which has the internal structure peculiar to the genus, but possesses a fascicu- 
late form, and increases by lateral gemmation; whilst in C. aggregatum, Billings, 
the corallum is also compound, and is produced either by lateral budding or by 
fission. In the genus Lridophyllum, one species (E. strictum, Edw. ana H.), 
increases principally or solely by calicular gemmation; but others (such as FL. 
Verneuilanum, Edw. and Haime, and £. Simcoénse, Billings), multiply by 
means of lateral budding. In the great genus Cyathophyllum, some species, 
such as C. ceratites, Goldfuss, C. obtortum, Edw. and H., C. Damnoniense, Phill., 
C. Zenkeri, Billings, C. helianthoides, Goldfuss, and the like are quite simple. 
Other species of the genus, such as C. truncatum, Linn., increase exclusively by 
means of calicular gemmation. In others, such as C. ewspitosum, Goldfuss, and 
C. articulatum, Wahl., we have a combination of calicular with lateral gemma- 
tion. In others, such as C. wquiseptatum, Edw. and H., C. radicans, Goldfuss, 
VOL. XXVII. PART III. 38 
