6 
CRETACEOUS CILIOPOUA 
of intcrinecliatc or transitional foi’ins, wc find that tlic form of a normally developed 
and veil preserved cell is constant within the limits of one species, and to a very 
large extent also within that of a genus as generally defined. 
This same assertion could, I fear, he scarcely relied upon, if made with regard 
to the seeoud point, Avhich I have mentioned, namely, the manner in which tlic cells 
are aiTanged during the progressive growth of the colony. Among fossils, where, as 
a rule, we have to deal with mere fragments, it is extremely difficult to make any 
observations on the real extent and development of a colony. Eut among recent 
CelleporcBi for example, I am acquainted with several instances in which one layer 
of cells grows over the second, and is covered hy a third. In the case of Cellepo- 
raria this growth is considered the normal one, hut while there are some species 
which, as a rule, incrust foreign substances in superposed iiTegular layers, they 
occasionally form regular globular masses, living ai)parontly free between sea weeds, 
although they might have been at an earlier stage attached to a small portion of the 
plant ; or they grow out into cylindrical or compressed branches. Again, the recent 
Eschar a cervicornis is sometimes found in crusting large masses of a foreign surface 
in a single layer, exactly like a Gellepora, until in some places two layers meet and 
form erect, variously branched, stems, which then possess every sign of regularity 
of an Escharoid colony. Now, as these variations in growth occur within the limits 
of a colony which we cannot by anj^ possibility refer but to one and the same 
species, I believe that the manner of growth is in a classifleatory point not an 
equally useful and reliable character,* as is the form of the individual cell. 
'\^'ith reference to the foregoing observations, and considering at the same 
tune the close relationship of the urccolate to the flustrinc form of the cell, I 
would propose a sub-division of the family into two sub-families, celltsfouinm and 
UEMBnAsiFouiKM, tliough I I’cadily admit that the division is framed more with a 
view to a practical than to a natural arrangement. I shall add brief charac- 
ters of those genera which are represented in the South Indian cretaceous deposits, 
with some remarks regaixling a few closely allied genera. The classification here 
adopted dilfers essentially from the one proposed by S mitt in Ofversigt of K. Ve- 
tensk. Akad. Eorhandlinger of 1867. 
A. CELLEFOFINJE. 
Cells urccolate, arranged in single or numerous alternating scries, colony 
incrusting or erect. 
There are four genera represented in the South Indian cretaceous rocks. 
1. Cellepora, Eab., 1780. 
Cells incrusting foreign substances in single layers, and arranged in quincunx. 
I have already! many years since drawn attention to the propriety of reseiwing 
Eabricius’ name in its original signification, and to the altogether unfounded 
* Busk divides according to it the present family into four or five — Memhraniporida, CelleporldcB, Escharida, 
Yinctdariidce, llijtpothoida, etc., and d’Orhigny, upon still minor considerations, into about a dozen. 
i" Eeisc der Novara, Geol. Theil, 1st Band, 1805, p. 120. 
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