CLASSIFICATION 61 



Meanwhile we are perforce necessitated to accept 

 a simple and ready, although more or less artificial, 

 system, such as that used by H. B. Brady in his 

 Eeport on the ' Challenger ' Foraminifera. 



The idea has lately been advanced by certain 

 authors that the earlier types of Foraminifera were 

 probably simple straight sandy tubes, without 

 partitions, followed by coiled and segmented or 

 chambered tests, and subsequently in later times by 

 a secreted shell of a calcareous nature. Detailed 

 observation, however, often refutes the best formu- 

 lated ideas, and it appears to have done so in this 

 case. Recent researches in the Cambrian Rocks of 

 New Brunswick and England have resulted in the 

 discovery of the following among other generic 

 types : Lagena^ Nodosaria (including Glanchilina), 

 Cristellaria, Globigerimr, and S'pirillina. All of these 

 forms have well-developed shell structures of a cal- 

 careous nature. With regard to the forms with 

 arenaceous tests, on the other hand, we find no evi- 

 dence of these until we reach the Upper Silurian 

 deposits, when we meet with Hypei^ammina^ and the 

 calcareo-arenaceous genus StacJieia. 



The classification which will be followed in the 

 succeeding pages of this book is that which has been 

 gradually evolved principally by the British school of 

 Rhizopodists — Wallich, Parker and Jones, Carpenter 

 and H. B, Brady — and which has been largely 

 emended and added to by the last-named author/ 

 With regard to the utility of this simpler method of 



1 See Eeport ChaUeiujcr, vol. ix. ' Zoology,' 1884, pp. 60-76. 



