162 MISCKLLANKOUS COMMUNICATIONS. 



if this is interleaved, as it always ought, to be a register of the localities 

 where the rarer species are to be found. His arrangement, as modified from 

 those of the best modern British botanists, is explained in a prefatory notice. 

 He adds the authority for each species and variety ; and for those varieties 

 which have not hitherto received an acknowledged name, he has framed one 

 as far as possible characteristic of their peculiarities, to which is appended the 

 name of the author who considers the plant as a variety, with a distinguishing 

 mark prefixed. This Catalogue of Mr. Leighton's displays evidences of 

 being constructed with extraordinary attention to accuracy and usefulness; 

 and although his entire list of cryptogamous vegetables does not extend be- 

 yond thirteen pages, it constitutes an admii'able approximation to perfection 

 in the accomplishment of its objects. 



Geological Excursion Professor Phillips, accompanied by several 



members of the Philosophical Institution of Birmingham, with some other 

 friends, lately made a geological excursion along the new line of canal to the 

 liime caverns at Dudley. The Basaltic columns at Rowley, the Wren's 

 Nest, and the Lime caverns were the principal objects of attention in the 

 day's excursion, and the Professor communicated the following observations 

 on the Geology of this interesting district : — Rowley Hills. The party visit- 

 ed a characteristic point of this undulated range of Basaltic rocks above the 

 Brades, where a considerable exposure of columnar rocks has been made for 

 the jHirpose of obtainmg materials for mending the roads. These columns 

 are jointed across, and the interest of the locality is augmented by the influ- 

 ence of atmospheric decomposition on the surface of the stone. Professor 

 Phillips took occasion to notice, with regard to the structure of Pyrogenous 

 rocks in general, and Basaltic rocks in particular, " that the directions of the 

 columns or prisms was almost invariably rectangular to the surfaces within 

 which the rock was confined and by which its rate of cooling was influenced. 

 If these surfaces are horizontal, the prisms are vertical; if vertical, the 

 prisms lie horizontally." The jointed structure of the prisms he referred to 

 that tendency observed by Mr. Gregory Watt in fused igneous masses to 

 solidify round centres into globular concretions ; and he pointed out the ex- 

 treme resemblance which these jointed rocks oflFer (when, under the influence 

 of atmospheric decomposition, the angular joints become flattened spheroids) 

 to the celebrated Kasekeller, which he has examined near Bertrich, in the 

 Eyfel — so called from the resemblance of these pillars, composed of flattened 

 spheroids, to heaps of cheeses — Wren's Nest. The rocks seen i:i this extra- 

 ordinary range compose the upper part of the Silurian system of Mr. Mur- 

 chison, and consist, in descending order, (as the canal penetrates them) of 

 Shale, called Lower Ludlow rocks, — Limestone of Dudley, and Wenlock Sliale. 

 The I,imestone of Dudley is in two divisions, separated by a good thickness 

 of Shaly beds, which, as well as the Limestone, are fossiliferous. Both of 

 the calcareous portions yield good Limestone, and as the inclination of the 

 strata in the hill is very steep, the entrance of the canal has afforded extra- 

 ordinary facilities for working these valuable rocks. The strata dip or de- 

 cline each way from the central line or axis of the Wren's Nest hill, which is 

 nearly north and south, and thus it happens that, in perforating this hill, the 

 strata are found on one side dipping 70° to the east, and on the other 45° or 

 more to the west. Remarkably long joints were observed in the subterra- 

 nean works, which were measured by Professor Phillips, and explained to the 



