COLLECTION, EXAMINATION, ETC. 305 



by dissolving the shells of the phosphatic chalk 

 Foraminifera in weak acetic acid. The residue must 

 be washed and dried with the greatest care, on 

 account of the extreme delicacy of the casts. 



Chalybite is sometimes found as an infilling of 

 the Foraminifera Saccammijia and Eudotliyra in 

 the Carboniferous Limestone ; and Haematite and 

 LiMONiTE are occasionally found as casts of Forami- 

 nifera in ferruginous limestones which are undergoing 

 decay. 



On Examiiung and Selecting the SJiells of Fora- 

 minifera. — In discussing the various methods of 

 mounting the Foraminifera we presume that one of the 

 first requisites is a lens or hand magnifier, by which the 

 various larger forms may be discovered and examined. 

 The majority of the species, however, are so small 

 as to make a microscope almost a necessity. Al- 

 though a triplet hand magnifier will be found useful 

 in going over the coarser siftings, the selection of the 

 smaller Foraminifera must be done with a compound 

 microscope, with objectives having a magnification of 

 at least 30 to 60 diameters. A very convenient 

 microscope stand is that known as the Wale's 

 Binocular, a form which the writer has had in 

 constant use for nearly twenty years, and which is 

 convenient not only on account of the space for deep 

 slides which the hollowed arm affords, but also for 

 the convenient clamping arrangement when the stage 

 of the microscope has to be tilted at high angles for 

 camera lucida or photomicrographic work. The 

 binocular arrangement is also to be reconmiended for 



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