86 BULLETIN OF THE MUSEUM OF COMPARATIVE ZOOLOGY. 
by numbers 1 to 5; the main sheet is shaded, and the anterior and pos- 
terior are located on either side of it; the faults are drawn as broken 
lines. Finally, a section drawn at right angles to the prevalent trend 
of the faults is given in Fig. 17; it is not constructed closely to scale, 
but indicates the general structure of the region. The abnormal Short 
Mountain fault, with downthrow on the southeast, which when first 
found seemed to endanger our generalization, is seen to be only a single 
exception to a well marked rule. No other explanation of the structure 
of the region than that by faulting seems admissible. 
It has been difficult and in most cases as yet impossible to trace the 
faults far to either side of the three trap ridges ; elsewhere, the surface 
is so heavily drift-covered, and the sandstone or shale ridges are so 
monotonous, that dislocations cannot be demonstrated. But it is in the 
highest degree probable that the faults are not limited to the belt 
of trap ridges; the uniformity of direction and of throw over the con- 
siderable district where we have traced them indicate their extension 
over a much larger area, where more patient search may yet detect 
them. 
The Triassic monocline must therefore be regarded as composed, in 
the Meriden—New Britain district, of a number of long and relatively 
narrow blocks, whose direction is oblique to the strike of their beds, but 
is in a most striking way accordant with the trend of the fundamental 
schists, where they are exposed to the southwest and northeast. I find 
it impossible to resist the conviction that this accordance is not due to 
chance, but that it points to physical dependence of the superficial on 
the deeper structure, as has been suggested in my earlier papers. 
CAMBRIDGE, Mass., March 27, 1889. 
