248 ANNUAL OF SCIENTIFIC DISCOVERY. 



diamonds of the Chapada Diamantina came from a conglomerate 

 and sandstone, which, from his description and specimens, appears 

 to be a tertiary rock of the same kiifd as that which 1'orms the 

 chapadas of the valley of the'Jequitinhonha. There is no itacol- 

 umite in the vicinity of Pitanga. The gravel is made up prin- 

 cipally of fragments of quartz and of pebbles of a sandstone like 

 that of the tertiary chapada, though somewhat harder than the 

 kind usually seen along the road. I do not believe that the 

 diamond ever occurs in the true palaeozoic itacolumite in Brazil, 

 but that it is derived from the tertiary sandstones. 1 ' Tliayer Ex- 

 pedition. Scientific Results of a Journey in Brazil, by Louis Agassiz 

 and his Travelling Companions. Geology and Physical Geography 

 of Brazil, by Ch. Fred. Nartt, Professor of Geology in Cornell Uni- 

 versity. Boston, 1870. 



CARIBBEAN SERIES OF TRINIDAD. 



Mr. Guppy, President of the Scientific Association of Trinidad, 

 stated before the Geological Society of London, that the northern 

 range of mountains of Trinidad is composed entirely of rocks 

 belonging to the Caribbean formation. The section from N.N.W. 

 to S.S.E. from the sea, through the valleys of Diego Martin, 

 Maraval, and St. Ann, shows the following succession of rocks in 

 ascending order : 



(1) Mica-slates, with quartzose sandstone; (2) crystalline lime- 

 stone : (3) argillaceous slates, with hard sandstones, conglome- 

 rates, and thin beds and strings of calcareous matter ; (4) compact 

 limestone, forming the Laventllle hills bordering the plain of 

 Caroni. The total thickness of these rocks in Trinidad is stated 

 by the author at upwards of 10,000 feet; and he is of opinion that 

 the thickness of the whole group is many times greater than this, 

 a portion of the series in Venezuela being probably inferior in 

 position to the rocks exposed in Trinidad. A high angle of incli- 

 nation almost everywhere prevails, the general range of dip being 

 from 30 to the vertical. After noticing the difficulty which 

 has hitherto existed in determining the age of the Caribbean for- 

 mation, from the want of fossil evidence, the author stated that he 

 found undoubted traces of the existence of organisms during the 

 depositions of these rocks. In the uppermost compact dark-blue 

 limestone (No. 4) obscure fossils occur. In the clay-slate and 

 quartz rocks (No. 3) underlying this limestone there are strings 

 and bands of calcareous matter which sometimes contain fossils. 

 In a portion of one of these strings, found by the author about 3 

 feet below the surface in the decomposed mica-slate forming the 

 soil of one of the valleys, he detected a structure which lie regards 

 as of animal origin, and as probably most nearly related to Eozoon. 

 He was unable to detect any traces of tubulation in it, but sug- 

 gests that this character may have been obliterated, as in the 

 Tudor specimen (" Quart. Journ. Geol. Soc." vol. xxiii., p. 257). 

 The chambers are said by the author to be more elliptical than 

 those of Eozoon canadense ; and for this and other reasons he pro- 

 posed to regard it as a new species, under the name of Eozoon 



