Geological Society of London. 137 



the " auricula " group of Pulvinulina is wanting in the Cretaceous 

 series, as also are SpirilUna and Cymhalopora, except that the latter 

 occurs in the Maestricht Chalk. Biscorhina and Calcarina^ make 

 their first appearance in the uppermost Chalk. The chief distinction 

 between the Cretaceous and the existing Eotaliuce was said to con- 

 sist in the progressively increasing number of modifications. The 

 authors concluded by disputing the propriety of regarding the 

 Atlantic ooze as homologous with the Chalk. 



Discussion. — The President suggested the possibility of some of the minute 

 Foraminifera being transported fossils derived from earlier beds than those in which 

 they are now found. 



Dr. Carpenter observed that the mode of examination to be adopted with 

 Foraminifera was different in character from that which was applicable to higher 

 organisms. The range in variation was so great that an imperfect examination of 

 Nummulites had sufficed to make M. d'Archiac reduce the number of species by one 

 half; and all the speaker's subsequent studies had impressed upon him the variety in 

 form and in sculpturing of surface on individuals of the same species. "When out of 

 some thousands of specimens of Operculina, 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 varieties connecting 

 all these different forms. He thought the same held good with Eptalinse, 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 bear- 

 ing 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. Kamsay remarked that geologists would be pleased to find Foraminifera 

 exhibiting, like other organisms, changes in some degree connected with the lapse ot 

 time. These low forms, however, could hardly afford criteria for judging of the age 

 of geological 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 Cephal- 

 opoda, 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. Seeley, Dr. Murie, 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, but 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 consideration. In 

 forming their tj'pes and subtypes the authors had carefully avoided minor differences ; 

 but they still thought that the modifications which were capable of being substan- 

 tiated were significant of a great lapse of time. A variation once established never 

 returned completely to the original type. In Globigerina., he stated that there were 

 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. 



2. "On the Infralias in Yorkshire." By the Eev. J. F. Blake, 

 M.A., F.G.S. 



The Infralias, i.e. the zones of Ammonites planorUs and Am. angu- 



