GEOLOGY. 2bO 



existed through enormous epochs, surviving not only the changes of phys- 

 ical conditions, but persisting comparatively unaltered, while other forms of 

 life have appeared and disappeared. Such forms may be termed " persist- 

 ent types " of life; and examples of them are abundant enough in both the 

 animal and the vegetable worlds. Among plants, for instance, ferns, club 

 mosses, and Conifine, some of them apparently generic-ally identical with 

 those now living, are met with as far back as the carboniferous epoch; the 

 cone of the oolitic Arancaria is hardly distinguishable from that of existing 

 species; a species of Pinus has been discovered in the Purbecks, and a wal- 

 nut in the cretaceous rocks. All these arc types of vegetable structure, 

 abounding at the present day;" and surely it is a most remarkable fact to 

 find them persisting with so little change through such vast epochs. Every 

 sub-kingdom of animals yields instances of the same kind, which are known 

 to have persisted from at least the middle of the Paleozoic epoch to our 

 own times, without exhibiting a greater amount of deviation from the 

 typical characters of these orders than may be found within their limits at 

 the present day. It is difficult to comprehend the meaning of such facts as 

 these, if we suppose that each species of animal and plant, or each great type 

 of organization, was formed and placed upon the surface of the globe at long 

 intervals by a distinct act of creative power. If, on the other hand, we view 

 " Persistent Types " in relation to that hypothesis which supposes the spe- 

 cies of animals living at any time to be the result of the gradual modifica- 

 tion of preexisting species, an hypothesis which is supported entirely on 

 negative evidence, and therefore wholly untenable in the present state of the 

 science, their existence would seem to show that the amount of modifica- 

 tion which living beings have undergone during geological times, is but very 

 small in relation to the whole series of changes which they have suffered. 

 In fact, palaeontology and physical geology coincide in indicating that all 

 we know of the condition in our world during geological time, is but the last 

 term of a vast and, so far as our present knowledge reaches, unrecorded 

 series of changes in the condition of the earth. London Literary Gazette. 



ON DEEP-SEA EXPLORATIONS. BY PEOF. W. P. TROWBRIDGE. 



The following is an abstract of a paper on this subject, communicated 

 to SiUiman's Journal, Vol. xxvi., Xo. 78, by Lieut. "\V. P. Trowbridge: 



The first systematic deep-sea explorations were undoubtedly made by 

 Commander C. H. Davis, U. S. X. This officer, in 184-5, while running a 

 line of deep-sea soundings across the Gulf Stream, obtained one cast of 1300 

 fathoms, and brought a specimen of the bottom, in the so-called " Stellwagen 

 Cup." In the succeeding year, in the same explorations, soundings were 

 made to the depth of 1500 and 2100 fathoms, without finding bottom; but, 

 in the latter case, the temperature of the water was recorded at the depth 

 named. In 1848, in the explorations off Cape Hatteras, the officer engaged 

 in the explorations lost his instrument, with 3300 fathoms of line out. In 

 these explorations of Commander Davis, 95 specimens of the bottom, and 

 25 specimens of water, at various depths, were brought up and preserved.* 



* These specimens from the ocean bottom were submitted to the late Prof. Bailer, 

 of West Point, for examination, who reported on them as follows: Ail the speci- 

 mens are of the highest interest, being filled with organisms, particularly the cal- 

 careous Polythalamia, to an amount that is really amazing hundreds of millions 

 existing in every cubic inch of these green muds. The most interesting specimen 



