IIUC:
In [294]: df.groupby(df.index.to_series().diff().ne(1).cumsum()).groups
Out[294]:
{1: Int64Index([27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37], dtype='int64'),
2: Int64Index([108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119], dtype='int64'),
3: Int64Index([352, 353, 354, 355, 356, 357, 358], dtype='int64')}