Layer Estimates:

Layer: Boston Block Groups (ID:0)
Count: 565
Extent:

XMin: -7924957.55917117
YMin: 5195051.70286891
XMax: -7895094.38641575
YMax: 5220539.21407782
Spatial Reference: 102100 (3857)

Layer: Open Space (ID:1)
Count: 1002
Extent:

XMin: -7924936.23459512
YMin: 5195177.8113653
XMax: -7889753.74163168
YMax: 5220564.68014257
Spatial Reference: 102100 (3857)