For 10 points, name this string instrument that is played between the legs by Yo-Yo Ma.
This instrument is featured in Johannes Maria Staud's composition Segue, which was premiered by Heinrich Schiff.  A concerto in E minor for this instrument was composed by Edward Elgar, and was notably performed by Jacqueline du Pre [PREY]. The two concerti composed for this instrument by Shostakovich were both written for Mstislav Rostropovich. Six suites for this instrument were composed by J. S. Bach, and were popularized by Pablo Casals. For 10 points, name this string instrument that is played between the legs by Yo-Yo Ma.
This instrument is featured in Johannes Maria Staud's composition Segue, which was premiered by Heinrich Schiff.  
{cello}