i8 9 3. NOTES AND COMMENTS. 405 



Work of this kind has been done abroad for some time. The 

 important biological results of Beecher, Clarke, and others, to which 

 we have often alluded (Natural Science, vol. i. pp. 606, 628 ; vol. iii., 

 pp. 15 and 163), almost entirely depend on very careful collecting, 

 inch by inch, through considerable thicknesses of rock. Munier- 

 Chalmas and Haug have done similar work in Europe of late years ; 

 but in England, if we except the admirable investigations of Lapworth 

 on Graptolite zones, which could only have been carried out by a man 

 thoroughly acquainted with the fossils, little of the kind has been 

 accomplished. We therefore welcome heartily the very interesting 

 paper by S. S. Buckman, on the Bajocian of the Sherborne district, 

 just published in the Quarterly Journal of the Geological Society (vol. xlix., 

 p. 479). Not only by his exact knowledge of, and previous work on, 

 the Stratigraphy of the Dorset Oolites, but by his prolonged studies of 

 their most important fossils, the Ammonites, he is excellently qualified 

 for work of the kind we have just described. Hence we are not sur- 

 prised to see that he goes very much further than previous geologists 

 in his subdivision of the strata, while that his subdivisions are not 

 illusory is proved by the possibility of tracing them in adjacent districts 

 and even on the Continent. Thus, he is able to show that there is the 

 same faunal succession in Dorset, Somerset, Gloucestershire, Nor- 

 mandy, Southern France, and Wurtemberg. This important point, 

 it must be remembered, could never have been proved under the old 

 system, when three zones were the most that were recognised in the 

 Inferior Oolite. Indeed, as the President of the Geological Society 

 remarked at the reading of the paper, " It was scarcely too much to 

 say that if rocks were to be studied in this minute way, the whole 

 of stratigraphical palaeontology would be revolutionised." 



The point in Mr. Buckman's paper that will most strike the casual 

 reader is his proposal of a new term, " hemera," as a subdivision of the 

 technical term " age." Practically the word means the time during 

 which a particular species was in existence. Thus " fuscee hemera " 

 means the period of time during which Oppelia fnsca lived in the 

 district in question. The species chosen to give names to hemerae are, 

 of course, those that only had a short existence, for the object is " to 

 mark the smallest consecutive divisions which the sequence of different 

 species enables us to separate in the maximum developments of 

 strata." The term, therefore, is a purely chronological one, neither 

 superseding nor a subdivision of " zone," so that the objections to it 

 made by speakers at the meeting fall to the ground. Mr. Buckman, 

 indeed, points out that species actually occurring together in a thin 

 band of rock, may really belong to different hemerae, a fact which can 

 sometimes be proved by examining the same stratum in another place 

 where its development is greater. 



Of the other very interesting results brought out by this detailed 

 method of work, such as the variations in the amount of deposition 

 and the migrations of the mollusca correlated therewith, we can hardly 



