Crosby.] 54 [October 2, 
rock itself is very compact and massive, of a dark bluish-drab to 
black color, and has a strong resemblance to the Trenton limestone 
of New York. Interstratified with it are occasional beds, one to 
twenty feet thick, of soft thin-bedded slates and shales which are 
frequently highly ferruginous and have polished and glistening sur- 
faces. It is chiefly by means of these argillaceous beds that we are 
able to observe the dip of the limestone. 
Besides many subordinate warpings, the compact limestone pre- 
sents one grand anticlinal fold invoiving the whole of the formation 
so far as exposed. On the Laventille Hills, Point Gourde, and the 
island of Gaspari the limestone dips to the north,— toward the 
mountains; while on the Diego Islands and the Cotoras (or Five 
Islands) the dip is southerly. The dip is usually steep, thirty to sev- 
enty degrees. Pato, which I have not visited, probably belongs on 
the north side of the arch. The crest of the anticlinal has been 
removed by denudation, forming the east-west passage between the 
islands. The position of the limestone on the Laventille Hills would 
seem to indicate that the anticlinal experiences a southerly deflection 
at this point, conforming in trend with the base of the mountains, of 
which these limestone elevations are the foot hills. The evidence all 
favors the view that the limestone islands, like the boca islands, have 
been fashioned by atmospheric agents and were isolated by the same 
subsidence that produced the bocas. 
The Caribbean Group, as thus limited, is probably all Pre-Cam- 
brian, or, what is the same thing, Pre-Paleozoic. It has yielded but 
few fossils, and these are all from the highest beds, being found in 
strings and bands of calcareous rock, which, in the San Francois 
Valley, immediately north of the Laventille Hills, are intercalated in 
the mica slate and aryillite forming the upper part of the third series. 
Here, again, we are indebted to Mr. Guppy for the totality of our 
knowledge. An interesting structure, probably organic, has been 
described by him under the name of Hozoon Caribeum. Two corals 
have been made out, one of which, a minute species, he names 
Favosites fenestralis, finding its nearest analogue in F. fibrosa; and 
the other is regarded as near Petraia bina Lonsdale. In addition 
there are distinct remains of Echinodermata; of these he says: 1— 
“There are plates, stems, and spines scattered through the stone; the 
most perfect consisting of five ambulacral plates and four pairs of 
1 Proc. Sci. Assoc. Trinidad, I1, 107. 
