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V. " Researches on the Foraminifera." Fourth and concluding 

 Series. By W. B. CARPENTER, M.D., F.R.S., F.G.S., 

 F.L.S. &c. Received June 14, 1860. 



(Abstract.) 



The author in this communication brings to a conclusion that 

 series of inquiries into the structural and physiological characters of 

 typical forms of Foraminifera, which he had been induced to work 

 out for the sake of turning to the account of Zoological science the 

 valuable collections made by Mr. Jukes in the Australian Seas and 

 by Mr. Cuming in the Philippine. 



The first genus now treated of is Polystomella, the smaller and 

 simpler forms of which have long been known, and of which the 

 structure, so far as it can be elucidated by the examination of such 

 specimens, has been already described with great care and accuracy 

 by Professor W. C. Williamson. But in the comparatively gigantic 

 and highly developed Polystomella of the Australian and Philippine 

 series, a feature exists which is scarcely discernible in the humbler 

 forms previously examined that feature being the extraordinary 

 development of the canal-system. A spiral canal runs along the 

 inner margin of either surface of every whorl; from this canal a 

 series of arches is given off, of which one passes down between every 

 two adjacent segments, uniting it with the other spiral canal ; whilst 

 another set of straight branches passes directly towards the surface 

 of the shell, through the thick calcareous deposit which covers in the 

 depressed centre of the spire, and which extends as far as the last- 

 formed spire. From the connecting arches, successive pairs of diverg- 

 ing branches proceed at frequent intervals ; these, in the last whorl, 

 make their way to the surface of the shell, and (when the shell is 

 newly formed) open close on either side of the septal band ; though, 

 as the shell increases in thickness by subsequent deposit, the increased 

 divergence of the branches separates their mouths from each other ; 

 and it very commonly happens that the two contiguous branches 

 diverging from different arches meet and open by a single external 

 pore half-way between the septal bands. When one whorl, however, 

 has been surrounded by another, this radiating canal-system of the 

 inner whorl does not usually continue itself directly into that of the 

 outer (though such a continuation is not unfrcquently seen), but 



