Seeking spatial data for very specific administrative boundaries in Ontario

This looks to me like a one degree wide and half degree high sheet layout of topographic maps similar to NTS.

Created with QGIS using vector raster. The numbering looks like a combination of West and North coordinates in 1/10 degrees.

This map contains an overview of 1:100,000 maps with the same numbering scheme:

http://www.mnr.gov.on.ca/stdprodconsume/groups/lr/@mnr/@water/documents/document/285331.pdf

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EDIT

As a workaround, you can download the 50k NTS index from ftp://ftp2.cits.rncan.gc.ca/pub/canvec/province_gml/on/canvec_gml_ON_LI.zip The 100k index is just a concatenation of 4 adjacent 50k tiles. I added that to my QGIS map, and created the numbering from the XMIN and YMIN values of my polygons:

I found maps using the scale and sheet layout, but numbered according to the NTS here:

http://www.geologyontario.mndmf.gov.on.ca/gosportal/GeologyOntarioFAST/pubs/M5/m5_index.html

http://www.geologyontario.mndmf.gov.on.ca/gosportal/GeologyOntarioFAST/pubs/NOEGTS/noegts_index.html

Looking for NOEGTS, I came across this site:

http://www.mndm.gov.on.ca/en/mines-and-minerals/applications/ogsearth/geology-terrain-noegts

The grid you see should be the one you want. If you have Google Earth, you can play with the available kml file, or download the whole dataset.

I think what you are initially after is http://search.library.utoronto.ca/details?852485 but I doubt these are available online.

Try the LIO Metadata portal.

Search for Crown Land Use Atlas and you'll find a couple of items that may be what you're looking for.