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XXV. Researches on Foraminifera. Fourth and concluding Series. 

 By WILLIAM B. CARPENTER, M.D., F.E.S., F.G.S., F.L.S. 



Eeceived June 14, Bead June 14, 1860. 



172. I HAVE now to bring to a close my account of the structure of those typical forms 

 of Foraminifera which it has been my object to elucidate, by a description of four 

 remarkable generic types ; of which the first, Polystomella, has long been known, but 

 has been hitherto very imperfectly comprehended; the second, Calcarina, has never 

 been carefully studied ; the third, Tinoporus, has only been very imperfectly known in 

 one of its forms ; and the fourth, Carpenteria, is altogether new. Each of these will be 

 found to present features of interest peculiarly its own ; Polystomella being remarkable 

 for the very symmetrical distribution of its canal-system, whose existence and whose 

 relation to the multiple fossa; upon its surface have hitherto been altogether overlooked ; 

 Calcarina being distinguished by the extraordinary development of its " intermediate" 

 or rather " supplemental skeleton," and by the amplification of the canal-system for its 

 nutrition ; Tinoporus presenting us with a type of structure that is intermediate between 

 the Eotaline group (to which it is allied in the character of its individual chambers) and 

 the Orbitoline (to which it approximates in its mode of growth), and that helps us 

 greatly in the interpretation of the structure of the fossil Orbitoides; and, lastly, 

 Carpenteria furnishing us with a connecting link of the most striking significance between 

 Foraminifera and Sponges. 



Genus POLYSTOMELLA. 



173. History. Of the minute shells to which the generic name Polystomella is now 

 assigned, one species, now known as P. crispa, seems to have early attracted the atten- 

 tion of conchological observers and collectors, on account both of its beauty and of the 

 frequency of its occurrence ; having been described and figured more than a century ago 

 by PLANCUS and GUALTIERI, and adopted by LINNJEUS under the designation Nautilus 

 into his ' Systema Naturae.' By this designation it continued to be known from the 

 time of LINNAEUS to that of LAMARCK ; having been described and figured by WALKER, 

 SOLDANI, FICIITEL and MOLL, MONTAGUE, DILLWYN, and many other writers of the latter 

 part of the last and the early part of the present century. Its dissimilarity to Nautilus 

 was first clearly pointed out in 1822 by LAMARCK; who conferred upon it the generic 

 distinction Polystomella, apparently under the impression that the numerous pits on its 

 surface are really multiple mouths of passages leading directly to its chambered cavity. 

 His definition of the genus, contained in the First Edition of his ' Animaux sans Ver- 

 tebres ' (torn. vii. p. 625), is as follows : " Coquille disco'ide, multiloculaire, a tours 



