102 REPORT — 1860. 



were gnawed before they were deposited there. Moreover, if these Troglodytae follow 

 the habits of their congeners in this latitude at present, they will be found to seek 

 external, and even distant places for the purpose indicated. Badgers, for instance, 

 resort to the same place nightly ; and the ground glitters with the elytra of beetles, 

 which at one time of the year constitute their principal food. It is an ill bird that 

 fouls its own nest. The cleanly habits of dogs, too, are well known. 



A brief notice will suffice to mark the site of the second cave for future examination. 

 It is on the same coast-line, and about the same sea-level, but further to the eastward. 

 Like the former, its walls have been removed. The floor was covered with bones, which 

 were shovelled into the sea when it was first broken into by the quarrymen. 



The particulars of the third cave will at this time be more interesting, perhaps, 

 because with some of the same remains of Carnivora mentioned above, flint-implements, 

 apparently of human workmanship, have been obtained. 



This cave is situated on the main land, and has a large open entrance half-way up 

 the cliff, known to the inhabitants by the name of "the Hoyle." I am not aware 

 that it was examined with a definite purpose till about twenty years ago, when Major, 

 afterwards Colonel, Jervis and Major Pugett exhumed two so-called flint celts, and one 

 of metal, which were sent to a museum in London. Lately a more careful examination 

 has been made of the contents of the red loam which constitutes the floor of what may 

 be called the first chamber of the long winding passage of which this cave consists. 

 Teeth of the bear and hyaena were discovered in this deposit, together with a consider- 

 able accumulation of sheep, pigs, and other existing animals. Here also are fish-bones, 

 mixed with littoral shells like those of our present sea; among them may be named 

 Patella, Cardium, Purpura lapillus, Mytilus, Liltorina liltorea, and Natica monili- 

 fera. Most of these shells are found also in the raised beaches which appear at different 

 heights ail round the adjacent coasts. 



Of the filling of these caves we have possibly some examples in the deep holes 

 which occur in water. courses, over mountain limestone, in the neighbourhood, and 

 which receive the mud and water after every glut of rain, for very many years, without 

 becoming choked or full ; but something more in the nature of a flood would really 

 sometimes appear to be necessary to account for some of the phenomena. 



On the Selection of a Peculiar Geological Habitat by some of the rarer 

 British Plants. By the Rev. W. S. Symonds, M.A., F.G.S. 



The Rev. Mr. Purchas, who is now engaged on the Botany of Herefordshire, has 

 divided the county of Hereford into twelve districts, and Mr. Symonds has been struck 

 by the apparent selection of a peculiar geological habitat by some of the rarer British 

 plants. 



The Snowdonian plants appear to affect the bands of volcanic ash that are inter- 

 stratified with rocks of Snowdon. 



Lychnis viscaria grows in four botanical districts out of five in Great Britain on 

 Greenstone; it grows on Stanner rocks, near Kington, with Scleranllius perennis. 

 Carex montana is only found on the carboniferous limestone. Lathyrus Aphaca, in 

 Worcestershire, affects the Keuper marls and sandstones. 



Mr. Symonds asks his brother naturalists especially to observe the flora of isolated 

 trap rocks, and do him the favour of forwarding to him the result of their observation. 



On the Geological System of the Central Sahara of Algeria. 

 By the Rev. H. B. Tristram, M.A., F.L.S. fyc. 



The paper, of which a short summary is appended, was compiled from the notes 

 and observations made during a six months' travel in the Sahara. The writer has no 

 pretensions to being a geologist, nor was geology the object of his wanderings. 



But as so little is known respecting the characteristics of this portion of North 

 Africa, he has not hesitated to give the result of his observations, in the hope that 

 the attention of more able and scientific naturalists may be directed to so interesting 

 a field. 



On leaving the Atlas crest, and descending its southern slopes, we soon come upon 

 the secondary rocks, which are the prevailing formation of the whole country between 

 the Atlas and Laghouat. This district for about 400 miles due south is rocky, 



