Part 2: Researches on the Foraminifera

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                                cimens) being .20 of an inch; whilst of the specimens which I
have seen from the West Indian and Aegean seas, none ex
ceed .12 of an inch.  Mr Carter <sup>1<sup>, however, describes under
the name of <u>Orbitolites Malabaricus</u> a fossil <u>Orbiculina</u>
(S90), <s>of</s> whose specific identity with the type before us I
see no reason to doubt, as attaining a diameter of from
7 to 8 lines. The thickness of the disk is usually less in
proportion to its diameter, than it is in <u>Orbitolites</u>; but this
is by no means a constant difference, depending as it does
merely on the relative increase <s>development</s> of the columns of  sar
code in the vertical direction, as compared with the exten
sion of the surface by the addition of new annular bands.
84. On more closely comparing the marginal portion of such a disk with the corresponding portion of one of those forms of <u>Orbitolites</u> in which the concentric annula
tion is strongly marked externally, whilst the transverse divisions of each annulius are scarcely indicated (§49), 
no <del>perceptible<del> <sup>essential<sup> difference is perceptible between them; 
<sup>and although<sup> these transverse diversions are usually but very faintly 
indicated in <u>Orbiculina<u>, yet they are sometimes very 
obvious, as is seen in Fig. 2, 6, and on a larger scale in Fig. 17. In the fossil <u>Orbiculina<u> just adverted to, the surface
-markings (Fig. 24,25) are entirely conformable to the or-
dinary type of <u>Orbitolites<u>. The margin itself exhibits one 
or more ranges of pores (Fig. 13, 24) arranged after precisely the same fashion as those of <u>Orbitolites<u>.
85. The internal structure of <u>Orbiculina<u> presents such a general conformity to that of <u>Orbitolites<u>, that it will 
not be requisite to do more than specify the points of 
- - - - - - - -
1. Annals of Natural History, New Series, Vol. XI, p. 425 

                            
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Manuscript details

Author
William Benjamin Carpenter
Reference
PT/53/8
Series
PT
Date
1856
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Part 2: Researches on the Foraminifera, 1856. From The Royal Society, PT/53/8

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