Dr. F. H. Batch— A Neiv British Phonolife. 149 



species, firstly, by its circular outline ; secondly, by the nucbal notch 

 reaching backwards nearly to the centre of the carapace ; thirdly, 

 by the different slope of the nuchal suture. 



The fauna of the " Colonic Haidinger " shows the same composition 

 as the lowest Graptolitic horizon of stage E — e 1. The most common 

 fossils of this "colony" being Monograptus Becki, Barr,, and Rastrites 

 peregrinus, Barr. 



Having no sufficient materials, I will not discuss the question if 

 the shields called Discinocaris should be regarded as opercula of 

 Cephalopods or carapaces of Phyllopodiform Crustaceans ; but it 

 must be remarked that no trace of Cephalopods has yet been dis- 

 covered in the " Colouie Haidinger." 



III. — A New British Phonolite. 



By Fredekick H. Hatch, Ph.D., F.G.S. 



(By permission of the Director- General of the Geological Survey.) 



TN working out, at the request of Sir Archibald Geikie, the petro- 

 graphy of the Lower Carboniferous Volcanic rocks in Had- 

 dingtonshire (the results of which I propose shortly to publish), I 

 have been led to examine the igneous material that builds up the 

 isolated hills (nechs), situated on the margin of the volcanic area 

 of the Garlton Hills. Among these, the rock of Traprain Law 

 especially attracted my attention. It is a close-grained, dark brown 

 to grey rock. Some varieties have a glistening or greasy surface, 

 and are speckled over with dark spots, while others show glancing 

 cleavage surfaces of a clear glassy felspar (sanidine). 



The stone is quarried at the foot of the hill. On examining the 

 broken material in the quarry, I noticed a tendency to split into 

 rather thin plates. This "platy fracture," taken in conjunction with 

 the fact that the stone has a remarkably sonorous ring under the 

 hammer, and gives a metallic clink when small fragments are rattled 

 together, might perhaps have suggested its real nature. But it was 

 not until I had studied a series of thin sections that the true character 

 of the rock became apparent, Microscopic examination shows that 

 the rock is a trachytic -phonolite, and thus adds another to the sparsely 

 developed nepheline-rocks of the British Isles. 



As I intend to describe this occurrence more fully elsewhere, I 

 will confine myself in this place to a brief description. The rock 

 bears no resemblance to the well-known phonolite of the Wolf Rock, 

 described by Mr. Allport in 1871. It differs from that rock in the 

 absence of members of the hauyn-nosean group, and by an inferior 

 development of nepheline. 



Instead of occurring in clearly discernible crystals, as in the 

 Cornish rock, the nepheline of the Traprain Law phonolite is 

 confined to small colourless to cloudy patches, or is interstitially 

 wedged in between the felspar-lathes of the ground-mass. The 

 satisfactory identification of nepheline when thus developed is the 

 source of much trouble and vexation of spirit. Taking refuge in 

 micro-chemical methods, I found that a drop of hydrochloric acid, 



