TRANSACTIONS OF SECTION C. 661 



primigenius in the Paris Museum, which is nearly five metres in heig-lit and 

 Avhich is exceeded by a specimen at St. Petersburg. The gxeat Dinotherium of 

 Pilierimi in Greece, found by Professor (iaudry himself, is of greater size still. The 

 author expressed his satisfaction at finding that among British paleontologists there 

 were now several who devoted themselves to the vertebrate as well as to invertebrate 

 remains. 



4. Note on the lielaiion of the Percentage of Garhonic Acid in the Atmosphere 

 to the Life and Groivfh of Flants. By the Rev. A. Irving, D.Sc, B.A., 

 F.G.S. 



The author refers to the discussion raised recently on this question in the pages 

 of the ' Geological Magazine.' In order to test the hypothesis adopted by Professor 

 Prestwich, three series of observations liave been made during the past summer on. 

 plants exposed, under similar physical conditions, to atmospheres of difi'erent com- 

 positions. The evidence obtained all points in one direction, and goes to show 

 that, with an increase of the percentage of carbonic acid up to about that of the 

 free oxygen present, the vigour of plant life and growth is also increased, so long 

 as the plants are freely supplied at their roots with water, as we have good reason 

 to suppose was the case with the vascular cryptogams from which the carbonised 

 materials of the coal-measures are for the most part derived. The author further 

 considers the theory as throwing some light upon a certain stage of development 

 of life upon the earth in later palajozoic time ; the great development of plant 

 growth in the carboniferous age having served as the means of storage of carbon in 

 the earth's lithosphere, and thus purified the atmosphere so as to render it fit for 

 the development of air-breathing forms of life in the Mesozoic Age. 



5. On the Occurrence of a Boidder of Granitoid Gneiss or Gneissoid Granite 

 in the Halifax Hard-hed Coal. Bij James Spencek. With a note by 

 Professor T. G. Bonnet. 



Many years ago, before the great importance of these boulders found in coal- 

 beds was recognised, a fine specimen was found in the Hard-bed coal at Dam Head 

 Pit, Shibdendale, near Halifax. It was a white hard rock .streaked with small 

 patches of a darker hue, almost as round as an orange, and about as large, and 

 most highly polished. Having had my attention again called to these boulders by 

 the discovery of quartzite boulders in the Black-bed coal at Leeds, two of them 

 having been sent to me to prepare slices for examination under the microscope, 1 

 have been on the look-out for specimens from our local coal-beds, and was very 

 fortunate to meet with one (in the spring of the present year 1888), which came 

 from Shibden Head Pit, near Halifax. The boulder is of a greyish colour, four 

 inches in length by about two and a half inches square. The angles have been 

 worn off and the faces smoothed and polished, and afterwards transversely 

 striated, the striae being most probably due to slickeusiding in the coal rather 

 than to glaciation. It may be of use to note the exact locality and horizon in 

 which the boulder was found. It came from the hard-bed coal at a depth of 

 about 150 yards from the surface, and from under the north side of a hill called 

 Barehead, in Shibdendale, near Halifax. The round boulder above mentioned 

 came from the same bed, and from under the south side of the same hill, the two 

 places being about half a mile apart. The geological horizon of the Hard-bed coal 

 lies at about 60 to 70 yards above the rough rock, the uppermost member of the 

 Millstone Grit series. 



After preparing thin slices and examining them under the microscope, it was 

 evident that the specimens presented a ditlerent structure from either of those 

 from the Black-bed coal. 



Professor T. G. Bonney, D.Sc, LL.D., F.R.S., &c., to whom a specimen had 

 been sent, kindly describes it as follows : — ' The boulder is one of unusual interest. 



