PROGRESS OF MICROSCOPICAL SCIENCE. 
33 
abundant means of distinguishing tlio most closely allied and minutely 
subdivided genera. 
Saccammina Carteri , a Foraminifer from the Carboniferous Lime- 
stone of Northumberland. — This discovery, which is in stated the valu- 
able Natural History Transactions of Northumberland and Durham for 
1871, we regret not having seen earlier. Still, as it is of interest, we 
lay it before our readers even now, as many of them may not have seen 
the volume which records it. It is a curious Foraminifer, and is 
amply illustrated by a very beautifully-executed plate in the end of 
the volumo. A question appears to arise whether apparently inde- 
pendent specimens were originally connected together. Thus, says 
the author of the paper, Mr. H. B. Brady, it is a question whether 
these bodies represent individual animals, or to what extent they may 
have been connected with each other when living. It is not at all 
unusual to fi nd on any weathered piece of the rock two segments con- 
nected by a stoloniferous tube — rarely three are found in this con- 
dition — and in one or two instances four or five have been noticed 
still retaining connection with each other. The bulk and weight of 
the segments and the comparative tenuity of the intermediate processes 
would be sufficient to account for the separation into single chambers, 
were this less constant than it is ; but there is no need to suppose that 
the single segment may not represent a perfect animal equally with 
the many-cliambered shell. Occasionally, though very rarely, a 
chamber is found with a round imperforate base and a single orifice at 
its apex, and if this is taken to correspond to the ordinary form of Lagena, 
the fusiform chambers may be regarded as analogous to the distomous 
varieties of that genus. The moniliform fossils might be compared to 
the Nodosarice, but that all that have as yet been met with have an 
aperture at each end of the series of segments, and, for anything known 
to the contrary, the test might extend itself indefinitely in either 
direction. The test is composite and arenaceous, the constituent par- 
ticles being fitted and cemented together so as to give a nearly smooth 
exterior. The size of the sand-grains and their mode of aggregation 
is a character of some importance amongst the recent Lituolida , but, as 
has been before stated, the process of mineralization has obscured the 
minute structure of the fossil in these particulars. The interior of 
the test is commonly smooth, resembling the recent Saccammina ; but 
it sometimes presents a surface of very short, delicate, labyrinthic, 
shelly ingrowths. This cancellated or labyrinthic structure is often 
met with amongst the arenaceous Foraminifera, and in some genera 
it is developed to an enormous extent. Here and there a specimen 
may be found with a sort of circular patch on the surface, which has 
the appearance of a cicatrix resulting either from the gradual closing-in 
of an orifice or possibly the reparation of some injury to the shell-wall. 
These slightly raised concentric markings, apparently deposited regu- 
larly from without inwards, occurring frequently and with consider- 
able uniformity, can scarcely be accidental. The positions in which 
they are generally noticed, viz. the sides rather than the ends of the 
segments, is an objection, though possibly not a fatal one, to the sup- 
position that they mark the closure of normal apertures. He has 
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