1878.] 49 [Crosby. 
of it; and Pato, which is also on this line, is the last point where 
this chain appears above the waters of the Gulf. From the Gulf of 
Paria, at a distance of from five to ten miles, we have a good profile 
view of the Northern Mountains, from Tucutche westward. And 
nowhere, probably, can the gradual dying out of a mountain range 
be seen to better alvantage than here; the gradation is almost per- 
fect, each peak or summit being a little higher than the one that 
follows, until we come to the Monos Boca; beyond this the incline is 
supported, but not broken, by the boca islands, and continuing on 
the same line the eye finally rests on Pato; the profile, no less than 
the map, view proving this islet essentially a part of the Trinidad 
range. The Point of Paria, viewed from the south, presents the 
same appearance of a mountain range gradually approaching its 
vanishing point. The inclination of the axis, however, is steeper in 
this case; and to this circumstance, chiefly, we owe the absence of a 
string of islands matching those through which the Trinidad range 
tapers out. The Point of Pefias, nevertheless, is essentially such an 
island, being connected with the main only by a low and narrow 
isthmus. 
The mountains of Paria and Trinidad form two parallel, over- 
lapping ranges with trends slightly oblique to the general course of 
the cordillera to which they belong, and to the strike of the rocks 
composing them. We have here, then, simply a fine example of the 
en échelon arrangement of mountain ranges so well displayed in our 
own Appalachian system and characterizing mountain regions gen- 
erally. And now we can see plainly what appears to have escaped 
the notice of observers heretofore, viz.: that in the Dragon’s Mouth 
there are two radically different kinds of bocas. The Monos, Hue- 
vos, and De Navios bocas are depressions in the Trinidad range of 
mountains, cutting thit range approximately at right angles; while 
the Boea Grande is the depression between two distinct ranges at 
the point where they overlap, and is, as we should naturally expect, 
much broader and deeper than the other bocas, and has a trend sub- 
stantially parallel with the ranges which it separates. 
The mountains of Tobago agree in lithology and structure with 
the Northern Mountains of Trinidad, and may, I think, be fairly 
regarded as another and last step in the en ¢cheion plan of the Carib- 
bean cordillera; and the interval between Trinidad and Tobago, 
having a maximum depth of sixty fathoms, is another Boca Grande. 
In such facts as this and the generally submerged condition of this 
PROCEEDINGS B. 8. N. H. — VOL. XX. 4 JANUARY, 1879. 
