528 ME. E. J. LECHMEEB GUPPT ON THE 



side the strata dip to the north, while on the southern side they dip 

 to the south ; the strike being about E.N.E. and W.S.W., coinciding 

 with the longest diameter of the hill. 



The foraminiferal rocks of Naparima consist of marls containing 80 

 to 90 per cent, of calcareous matter. Some of the beds contain 

 gypsum, but not to the extent or in the large-sized masses occurring 

 in the Nariva (Miocene) Series. When subjected to washing, about 

 one-half of the material passes off as fine mud containing minute 

 foraminifera (Glohigerina, Textularia, &c.) such as those found in 

 the white Chalk of England, also Calcaromma and coccoliths. Of 

 the remainder, one-half consists of indeterminable and amorphous 

 particles, bits of pumice, iron pyrites, &c. There are a number of rod- 

 like forms of a black colour and more or less glistening or metallic 

 subgranular texture. These may possibly be Lituolidce or similar 

 foraminifera and perhaps echinoderm spines and pteropod shells 

 impregnated with a compound of iron. The remaining half (= | of 

 the original material) is chiefly made up of shells of Glohigerina, 

 from among which the other foraminifera may be picked. This is 

 a true solidified Globigerina-ooze, corresponding in essential features 

 with that now found in the abysmal depths of the ocean. 



Under treatment with acid a specimen of this rock lost about 

 90 per cent. The residue was of a brown colour and showed little 

 else but amorphous particles. Here and there traces of fossils were 

 visible, probably fragments of radiolaria and sponge-spicules. In 

 other samples I have demonstrated clearly the presence of radiolaria 

 and other siliceous organisms. 



The " infusorial" character of the marls of South J^aparima was 

 referred to at pages 86 and 116 of the Geological Report on Trinidad. 

 There is as much variation in the physical properties and compo- 

 sition and in the organic contents of different samples of these marls 

 as in those of the foraminiferal beds. Nevertheless, many characters 

 are common to aU of them. They differ from the foraminiferal 

 marls in the large proportion of silica that they contain. This silica 

 is due to the presence of so-called infusorial fossils, the remains of 

 radiolaria and diatomaceae. The diatomaceae were described by 

 Greville in the fifth volume of the Journal of the Microscopical 

 Society. The polycystinse are similar to those of the Barbados, rocks 

 described by Ehrenberg in the ' Mikrogeologie ' and elsewhere. 



Eor purposes of a brief description I will select two samples of 

 the radiolarian marls. Of sample Wo. 1 from 30 to 40 per cent, is 

 removed by treatment with acid. The portion thus removed is 

 chiefly made up of foraminifera, the remainder consisting of radio- 

 laria, &c., and of iridescent scales and lumps of a whitish substance. 

 The simple washing and drying of a sample of this rock, without 

 the use of reagents, furnishes a material strongly resembling steatite 

 (French chalk). It might indeed be applied to the same purposes 

 as the latter is. This material consists of small scales and lumps 

 of a pearly grey colour and iridescent surface, and these form about 

 one-half of the rock, the remainder being fine siliceous particles 

 (radiolaria, &c.) and foraminifera. The latter are present in notice- 



