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XXVII. — On the Structure of the Shell and Soft Animal of Polysto- 

 mella crispa ; with some Remarks on the Zoological Position of 

 the Foraminifera. By W. C. Williamson, Esq., of Man- 

 chester. 



(Read December 20, 1848). 



The extensively diffused shells of the animals now designated 

 Foraminifera have long attracted the attention of zoologists. The 

 extraordinary abundance of recent species in sea-sands from every 

 part of the globe, and the vast ancient deposits, especially of tertiary 

 and cretaceous strata, presenting little more than accumulations of 

 their fossil remains, caused them to be noticed by many observers at 

 an early period : but from ignorance of their internal structure, and 

 more especially of their soft parts, these singular creatures, as is 

 well known, were handed over to the conchologists, who, up to the 

 present time have admitted them into their publications, and still 

 appear to claim them as a part of their own unquestioned domain. 



The vague guesses of speculative writers soon assigned to the cal- 

 careous structures a soft animal having the form of a Cephalopod. 

 De Montfort, though perplexed by the anomalous forms with which he 

 had to deal, especially with his " genres d'autant plus remarquables, 

 qu'ils ne presentent point de bouche ou d'ouverture proprement 

 dite " (' Conchyliologie Systematique,' vol. i. p. 15) ventured boldly to 

 assign to them an internal animal, indulging at the same time in a 

 multitude of guesses as to the way in which it could keep up a com- 

 munication with the surrounding medium. Notwithstanding the 

 worthlessness of these speculations, De Montfort evidently made some 

 accurate observations, and drew from them important inferences. 

 Speaking of his Polygenes cribratus, he says, " individuellement elle 

 est entierement criblee de pores, qui sont a jour. Organisation tres 

 digne de remarque, et qui sembleroit permettre le passage a autant 

 de bras qui, comme ceux des polypes, saisiroient leur proie a 

 l'instant ou elle s'approcheroit : analogue qui nous conduiroit aux 



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