1870.] * Porcupine* -Expedition Madrcporaria. 



299 



deposits in the Laurentian, Silurian, or in any other formation. The 

 " flysch," a great sediment of the Eocene formation, has heen considered 

 to have been formed at a great depth and under great pressure. Its singularly 

 unfossiliferous character was supposed to be due to the absence of life at 

 the depths of the ocean where the sediment collected. But this was a 

 theory of the early days of geology, when the destructive influence of che- 

 mical processes in strata upon the remains of organisms in them was hardly 

 admitted. 



The great value of such researches as those so ably carried out by 

 Thomson, Carpenter, and Jeffreys is the definite knowledge they impart to 

 the geologist, who is theorizing in the right direction, but whose notions 

 of the depth at which the sediments containing Invertebrata can be depo- 

 sited are indefinite. These researches contribute to more exact knowledge, 

 and they will materially assist the development of those hypotheses which 

 are current amongst advanced geologists into fixed theories. I do not 

 think that any geological theory worthy of the term, and which has origi- 

 nated from geological induction, will be upset by these careful investiga- 

 tions into the bathymetrical distribution of life and temperature. The 

 theories involving pressure and the intensity of the hardness of deep-sea 

 deposits will suffer from the researches ; but many difficulties in the way 

 of the palaeontologist will be removed. The researches tend to explain 

 the occurrence of a magnificent deep-sea coral-fauna in the Palaeozoic 

 times in high latitudes, and of Jurassic and Cainozoic faunas on the 

 same area, and they favour the doctrines of uniformity. They ex- 

 plain the cosmopolitan nature of many organisms, past and present, which 

 were credited with a deep-sea habitat, and they afford the foundations for 

 a theory upon" the world-wide distribution of many forms during every 

 geological formation. 



It is not advisable, however, to make too much of the interesting 

 identities and resemblances of some of the deep-sea and abyssal forms 

 with those of such periods as the. Cretaceous, for instance. In the early 

 days of geological science there was a favourite theory that at the expira- 

 tion of a period the whole of the life of the globe was destroyed, and 

 that at the commencement of the succeeding age a new creation took 

 place. There were as many destructions and creations as periods ; or, to 

 use the words of an American geologist, there was a succession of plat- 

 forms. This theory held back the science, just as the theory that the sun 

 revolved round the earth retarded the progress of astronomy. Moreover 

 it had that armour of sanctity to protect it which is so hard to pierce by 

 the most reasonable opposition. Nevertheless every now and then a 

 geologist recognized the same fossils in rocks which belonged to different 

 periods. A magnificent essay by Edward Forbes on the Cretaceous Fossils 

 of Southern India, a wonderful production and far before its age*, gave 

 hope and confidence to the few palaeontologists who began to assert that 

 * Quart. Journ. Gcol. Soc. vol. i. p. 79. 



