MUSEUM OF COMPARATIVE ZOOLOGY. 107 



from Gaylord's Mountain, but more olivine is present in the holocrys- 

 talline portions. Approaching the upper and lower contacts, there is a 

 gradual disappearance of the augite and a decrease in the coarseness of 

 texture; the augite disappears at the contacts, porphyritic crystals of 

 olivine become abundant, and the rock is extremely fine-grained and 

 glassy. Occasional pseud-amygdaloidal areas occur in the trap ; but 

 no vesicles due to the expansion of occluded gases have been observed. 



GROUP II. EASTERN TRAP RIDGES. 



Division I. Anterior Ridges. 



Locality 4. Section numbers, 26-28. Anterior at northern end of Totoket Mountain. 

 PercivaVs Report, pp. 344, 345. Percival's notation, A. 1. N. of E. II. 



The ridge anterior to Totoket has few strong outcrops ; the one here 

 referred to is at the north end of the main sheet in a stream bank, 

 east of S. W. Loper's, South Durham (Fig. 3). Best reached by stage 

 from New Haven to North Guilford. Base of sheet for a thickness of 

 eight feet consists of a breccia of scoriaceous trap and clastic material, 

 cemented together by quartz and calcite ; upper part extremely vesicular ; 

 uo upper contact found. Lower portion glassy and porphyritic. 



Locality 5. § mile S. E. of East Meriden. Peravnl'i; Report, pp. 302-305. Percival's 



notation, A. 1. of E. III. (3). 



The anterior to the long Durham range is traceable for many miles, 

 but is often heavily covered with drift. The bluffs of the ridge are of 

 the ordinary dense trap, and its back is as usual vesicular. About a 

 quarter of a mile south of Black Pond, near East Meriden, there is a 

 faint depression in its back, and here the ground is covered with 

 numerous fragments of sandstone containing pieces of vesicular and an- 

 gular trap (Fig. 13). A shallow opening would secure excellent speci- 

 mens. It seems as if there was here a depression in the surface of the 

 sheet, into which local fragments of trap were washed with sand from a 

 more distant source. 



Locality 6. West of northern end of Higby Mountain. Percival's Report, 

 pp. 362-365. Percival's notation, A. 1. of E. III. (4). 



The gap between Iligby Mountain and Chauncy Peak is followed by 

 the Meriden, Waterbury, and Connecticut River Eailroad, and by the 

 highway from Meriden tc Westfield (Fig. 4). A road branches from 

 the latter in the gap, and runs south on the amygdaloidal back of the 



