It. J. L. Gupprj — Naparima Rocks, Trinidad. 323 



and we are now aware that these two series pass gradually and 

 conformably one into the other. A similar result may hereafter 

 happen in regard to the Naparima marls and the Nariva Series. In 

 the meantime my opinion is based mainly upon conjecture, though 

 one point weighs a good deal with me, that is, the strong resemblance 

 of the Nariva beds to the strata now being deposited in the gulf 

 derived from the degradation of the Naparima beds ; and if this 

 inference is correct the Nariva Series must be later in date than 

 the foraminiferal marls. The resemblance I refer to is one not 

 only of mineral composition and mechanical aggregation, but of 

 organic contents, inasmuch as some of the deposits now being laid 

 down and (notably those off the mouth of the Sipero river) contain 

 foraminifera of the same character and in similar condition and of 

 similar frequency of occurrence as the Nariva beds. To take an 

 example, Globigerina is a very abundant organism, both in the mud 

 deposits off Sanfernando and in the Nariva beds, but in both these 

 deposits it is relatively much less abundant than in the foraminiferal 

 marls ; and the relative infi'equency of occurrence is due to the 

 destruction of the fossils in the course of the denudation and 

 redeposition of the marls. No such foraminifera now exist or can 

 exist in a living state in the gulf, though in my very first dredgings 

 ofi" Sanfernando I recorded Globigerina at every haul in shallow 

 water near the shore. That was before I had recognized Globigei-ina 

 in the rocks of Naparima, and, as 1 have already stated, the 

 foraminifera so dredged by me were fossils derived from the 

 Naparima marls. Also, I consider that the abundance of gypsum 

 in the Nariva Series is due to the breaking down and redeposition 

 of the foraminiferal marls, in course of which the carbonate of lime 

 existing in the latter was partly changed into sulphate. 



Eespecting the nature and origin of the Argilino of Naparima 

 Hill, I somewhat timidly expressed my opinion in former papers. 

 As I find that Messrs. Harrison and Jukes-Browne are substantially 

 of the same opinion as myself on the subject, I may take the 

 opportunity of restating it. The nature and origin of the Argiline 

 are similar to those of the Naparima foraminiferal and radiolarian 

 marls, and it contained similar Eadiolaria and Foraminifera. But 

 the Argiline has undergone a change consequent upon an alteration 

 in the form of its silica ; a change analogous to that which has 

 taken place in part of the so-called * cement ' of the White Hills 

 of Bendigo, Australia, described by me in the Proceedings of the 

 Geologists' Association of London, 1864, p. 409, and which consists 

 in an induration by probably a partial solution and redeposition of 

 the siliceous constituents. The whole mass of Naparima Hill is 

 thus affected ; but a similar change has partially and locally affected 

 other portions of the Naparima rocks. 



To my description of the Argiline of Naparima Hill published 

 in the Geological Society's Journal, November, 1892, p. 526, should 

 be added the remarks contained in my paper in the Trinidad Field 

 Naturalists' Journal, 1893, p. 7, as follows : " Beds of different, 

 texture occur in the Argiline, some being more sandy in composition. 



