Source : Webster's Revised Unabridged Dictionary (1913)

Subtreasury \Sub*treas"ur*y\, n.; pl. {Subtreasuries}.
   A subordinate treasury, or place of deposit; as, the United
   States subtreasury at New York. [U. S.]

Source : WordNet®

subtreasury
     n : a subordinate treasury or place of deposit