554 8. S. Buckman — The Term ' Hemera.' 



Finally, we must express our grave doubts about the high dips 

 which Dr. Spencer states that he saw in our Coral Eeef Series. 

 One of us resided for ten years in Barbados, traversed it in many 

 directions at various times, and examined nearly every gully in the 

 island as well as most parts of the great limestone escarpment, yet 

 he never saw any such high dips as Dr. Spencer mentions, except 

 where there was reason to suspect a landslip, and such landslips ar& 

 certainly common. We have noted low dips (of 4° or 5°) at 

 a few places, and some false - bedding which might mislead an 

 inexperienced observer but hardly one of Dr. Spencer's experience. 

 We cannot say that the high dips are always in slipped masses, but 

 we do think that the sloping beds specially mentioned by him near 

 Bath, "upon the flank of the mountain behind" the Bath Eeef 

 terrace, are in a mass that has slipped from the great escarpment above. 



Let our readers consider also what continuous dips of from 

 12° to 20° involve; a dip of 15° continued for only one mile on 

 the horizontal will bring in a thickness of 1,367 feet, and even if 

 the surface of the ground fell 300 feet in the direction of the dip,^ 

 it would leave a thickness of over 1,000 feet, whereas the greatest 

 thickness of combined Bissex Hill Beds and coral-reef limestones 

 proved by Mr. Easton's numerous borings all over the island is only 

 280 feet. 



It will be obvious that the differences between Dr. Spencer and 

 ourselves are so great and so difficult to reconcile that we are not 

 likely to convince one another by argument at a distance from the 

 field of dispute. Fresh observations are required, and above all 

 further collection of fossils must be made, before either party can 

 make any real addition to our knowledge of the geology of Barbados, 

 We have been in communication with Dr. Spencer, and we hope that 

 one of us may be able to meet him in Barbados next March, with 

 the view of discussing the evidence on the spot and of obtaining 

 fossils from the beds which he regards as of Oligocene age. In 

 the meantime we ask our readers to suspend their judgment on th& 

 questions raised by Dr. Spencer's paper. 



IV. — The Tkrm ' Hemera.' 



By S. S. Bl-ckman, F.G.S. 



NEAELY ten years ago I proposed the term 'hemera.'^ The 

 term is coming into use ; but, so far as I am aware, in the 

 majority of cases it is greatly misunderstood. From this causa 

 arise objections as to its use, such objections being based on the 

 misconception that the hemera is a subdivision of a zone. It i& 

 nothing of the kind. 



The original description may be quoted. " It is for a paleeontological 

 purpose that I propose the term ' hemera.' Its meaning is ' day ' 

 or ' time ' ; and I wish to use it as the chronological indicator of 

 the faunal sequence. Successive ' hemeree ' should mark the smallest 



1 " Bajocian of the Sherborne District " : Quart. Journ. Geol. Soc, 1893, vol. xlix, 

 p. 481. 



