465 



from the rest by having their shells perforated with large canals, oc- 

 cupied in the living animal by csecal prolongations of the mantle. 

 The presence of these perforations, which had previously been con- 

 sidered to be mere surface markings, Dr. Carpenter showed to be a 

 constant character of the Terebratulidse, and their absence an equally 

 constant character of the Rhynchonellidse ; whilst, in other families, 

 certain genera or subgenera are distinguished by their presence from 

 those in which they are absent. The validity of this distinctive 

 character has since been amply confirmed by Mr. Davidson in his 

 elaborate investigations of British Fossil Brachiopoda. 



Dr. Carpenter's first contribution to the minute study of the Fo- 

 raminifera was a memoir read before the Geological Society in 1850, 

 in which he showed the necessity of a careful microscopic inquiry 

 into the structure of the organisms of the class in question, for the 

 elucidation of their real nature and affinities ; and, taken in connec- 

 tion with Professor W. C. Williamson's previous memoirs on Poly- 

 stomella crispa, this memoir may be considered as having laid the 

 foundation for the truly scientific study of the Foraminifera, which 

 has since been vigorously prosecuted by Professor "Williamson, 

 MM. D'Archiac and Haime, and Messrs W. H. Parker and Rupert 

 Jones, as well as by Dr Carpenter himself. 



In the four memoirs on the minute structure of the most highly 

 developed forms of this class which Dr. Carpenter has contributed 

 to the * Philosophical Transactions/ he has described some most re- 

 markable types which were previously quite unknown ; he has given 

 a detailed account of the very complex organization existing alike in 

 the foregoing and in types previously well known by external con- 

 figuration ; he has demonstrated the entire fallacy of the artificial 

 system of classification hitherto in vogue, the primary divisions of 

 which are based on the plan of growth ; he has laid the foundation 

 of a natural system, based on those characters in the internal struc- 

 ture and conformation of the shell which are most closely related to 

 the physiological conditions of the animal ; and, finally, by the com- 

 parison of very large numbers of individuals, he has proved the exist- 

 ence of an extremely wide range of variation among the leading types 

 of Foraminifera ; often reassembling under a single species, varying 

 forms, which, for want of a sufficiently careful study, have been not 

 merely separated into distinct species, but had been arranged under 



