1872.] JOXES AND TAKKEE — CEETACEOTJS rOEAMrNIFEEA. 131 



same species. "When out of some thousands of specimens of Oper- 

 cidina, say, a dozen pronounced forms had been selected, such as by 

 themselves seemed well marked and distinct, it might turn out that 

 after all there was but one species present, with intermediate varie- 

 ties connecting all these different forms. He thought the same held 

 good with Rotalince, and that there were osculant forms which might 

 connect, not only the species, but even the genera into which they 

 had been subdivided. This fact had an important bearing on their 

 genetic succession, especially as it appeared that some of the best- 

 marked types were due to the conditions under which they lived. 



The temperature in tropical seas differed in accordance with the 

 depth so much, that when 2000 fathoms were reached a degree of 

 cold was attained such as was to be found in high latitudes ; and 

 in consequence the deep-sea forms in tropical latitudes assumed the 

 dwarfed character of those in shallower seas and nearer the Pole. 

 He suggested caution in drawing inferences from forms so subject 

 to modification, both spontaneous and due to the depth of the sea, 

 especially as connected with abundance of food. 



Prof. Ramsay remarked that geologists would be pleased to find 

 Foraminifera exhibiting, like other organisms, changes in some 

 degree connected with the lapse of time. These low forms, how- 

 ever, could hardly afford ciiteria for judging of the age of geolo- 

 gical formations, while at the same time such ample means were 

 afforded by the higher organisms for coming to a conclusion. 

 He cited, for instance, the Cephalopoda as proving how different 

 were the more important forms of marine life in Cretaceous times 

 from those of the present day. He thought that no one who had 

 thoroughly studied the forms of ancient life would be led to ignore 

 the differences they presented, as a whole, from those now existing. 



Mr. Seelet, Dr. MupaE, and Mr. Hicks also made some remarks 

 on the paper. 



Prof. Jones, in reply, observed that the question of whether the 

 Foraminifera in a given bed were derived or not was to be solved 

 partly by their condition and partly by their relative proportions, 

 and that in most cases sufficient data existed on which to found a 

 judgment. He agreed with Dr. Carpenter as to the existence of 

 extreme modifications ; and it had been his object to ignore such as 

 seemed due to ordinary and local causes, and to group the forms in 

 accordance with certain characteristics. Whether the classification 

 was right or wrong, it was necessary, for the sake of increasing 

 knowledge, that fossils of this kind should be arranged in groups ; and 

 whether these were to be regarded as truly generic was a minor con- 

 sideration. In forming their types and subtyj)es the authors had 

 carefully avoided minor differences ; and they thought that the 

 modifications which were capable of being substantiated were sig- 

 nificant of a great lapse of time. A variation once established never 

 returned completely to the original type. In Glohigerina, he stated 

 that there wei^e in Cretaceous times 8 forms, in Tertiary 12, at the 

 present time 14 ; and these modifications he regarded as equivalent 

 to the specific changes in higher animals. 



