---------Original ID Request Text----------
Subway Sphinx - prepupal caterpillar

My husband found this sphinx caterpillar in the Temple U. subway station in North Philadelphia and brought it home for me. No idea where it came from or what its foodplant was. It was in the "prepupal wandering" stage, so color and texture are probably not normal.

Key features, other than size and color:
Granulose integument
Four "spikes" on thorax
Diagonal white lines, rear one extending onto horn
Horn green and granulose

The caterpillar has disappeared into a container of soil now, so I can't take more photos w/o digging it up.