564 Reviews — Geological Survey of England and Wales. 



America. Mr. Murray lias found tliem in Newfoundland, and Mr. 

 Selwyn in Nova Scotia." The B. explanatum of Mr. Hicks from 

 the Lower Arenig (Llandeilo) rocks of Wales is apparently some- 

 thing quite different ; and in microscopic structure would seem to 

 be similar to that of the Nematoxylon of the Devonian, if it be a 

 plant at all, and not a marine organism. — Dawson, " Fossil Plants of 

 Canada," 1871, p. 79. 



I desire, in conclusion, to express my obligation to Dr. J. W. 

 Dawson, of Montreal, for valuable assistance willingly rendered, and 

 to Mr. Leo Lesquereux, of Columbus, Ohio, for kind and prompt 

 replies to letters of inquiry.^ 



laiBA^^IIB'VT'S. 



L — Memoirs of the Geological Survey of England and Wales. 



1. The Eruptive Eocks of Brent Tor and its Neighbourhood. 

 By Frank Eutley, F.G.S. 



2. The Chim^roid Fishes of the British Cretaceous Eocks. 

 By E. T. Newton, F.G.S. (London, 1878.) 



n^HE above works on very different subjects indicate the progress 

 I of research carried on by the Geological Survey, and form 

 valuable additions to their other publications. The first memoir 

 comprises a description of a limited district around Brent Tor, 

 which was surveyed nearly fifty years ago by Sir H. De la Beche, 

 recorded in his Eeport on the Geology of Cornwall, Devon, and 

 West Somerset, to which work the investigations of Mr. Eutley 

 may be considered as a sequel. Within the district of about sixty 

 square miles occur many highly-interesting and peculiar eruptive 

 rocks, some intruded through, and others interbedded with, the 

 Carboniferous and Devonian strata which lie on the west of Dart- 

 moor. The object of the author being to elucidate (1) the mineral 

 composition and structure of the different rocks as oi)served in the 

 field, and of which a detailed account is given in the first part, 

 illustrated by some artistic sketches of their physical features and 

 other characters in plates 2 to 6 ; (2) to investigate, by means of 

 the microscope, the more minute structure of selected specimens of 

 the rocks, a mode of research which, during the last few years, has 

 materially assisted the labours of the petrologist ; — twenty-seven 

 different rocks are clearly described, and some of them are beauti- 

 fully illustrated by enlarged coloured figures (plates 8 to 10) from 

 Mr. Eutley's careful microscopic drawings. The third part com- 

 prises remarks on the probable conditions under which the igneous 



1 "Proceed. American Philosophical Society" (Philadelphia), vol. xvii. No. 100, 

 1877, p. 163, etc., Leo Lesquereux, " On Land-plants recently discovered in the 

 Silurian Rocks of the United States." Eead October 19th, 1877; printed January 

 7th, 1878. 



Fsilophytum gracillimum (p. 164), sp. n. 



cornutum (p. 165), sp. n. 



Annularia Morning eri {^. 166), sp. n. 



Sphenopliyllum prim(Bvum (p. 167), Lesqx. 



Frotostigma aigillarioides (p. 169), sp. n. — Editor. 



