MUSEUM OF COMPARATIVE ZOOLOGY. 115 
Locality 24. Section numbers, 120-123. Highland Lake. Percival’s Report, pp. 336- 
838. Percival’s notation, P. 4, E. II. (5). 
The ridge posterior to Chauncy Peak is cut near its southern end 
by the Meriden, Waterbury, and Connecticut River Railroad, a quarter 
of a mile east of Highland station (Fig. 4). An excellent exposure. 
Under contact not shown. Trap generally dense ; originally glassy and 
porphyritic; not locally close-grained at upper contact ; upper portion 
extremely vesicular ; sand grains filling vesicles and fissures, their lines 
of deposit conforming to the irregularities of the trap surface (Fig. 14) ; 
these deposits connected with the sandstone above by necks ; inequali- 
ties in upper surface of trap covered by conformably stratified sandstone. 
Numerous angular, vesicular, large and small fragments of trap lying 
above the sheet ; spaces between these filled with irregularly but con- 
formably stratified sandstone ; vesicles in fragments filled with sand ; 
some of the vesicles only partly filled, and in such cases the upper sur- 
face of the filling is parallel to the dip of the Triassic monocline. 
Locality 25. Section numbers, 124-131. Hartford Ave. and N. Stanley St., New Brit- 
ain. Percival’s Report, pp. 381, 384. Percival’s notation, P. (e), E. LV. I. (7). 
The overlapping ends of the small trap ridges on the northeastern 
border of New Britain are regarded as faulted portions of a single pos- 
terior sheet ; a small stream flows between them. The eastern ridge is 
quarried, and discloses the base of the sheet ; the upper contact is found 
where the stream runs on the back of the western ridge. 
Trap generally dense, but containing local amygdaloidal areas, sur- 
rounded by dense trap, as if produced by intermittent flowing; very 
vesicular at upper surface, and originally possessing a glassy base ; sand- 
stone immediately above contains water-worn grains and fragments of 
much decomposed trap. 
Locality 26. Section numbers, 152-156. Near Trinity College, Hartford. Percival’s 
Report, pp. 385, 386. Percival’s notation, P. (¢), E. IV. I. (9). 
This ridge is of doubtful relationship: it may be a second posterior 
sheet, and therefore not directly comparable with the previous examples. 
Its middle portion and base are well exposed in large quarries. The 
trap is generally dense; triangular areas between the feldspars contain 
a little glass ; the lower portion is brecciated and extremely scoriaceous ; 
obsidian-like grains of trap in shale immediately under trap ; upper 
portion vesicular, but overlying sandstones not seen. See special 
account. 
