located at a distance between 10$''$ and 20$''$ from the star. This distribution was already known for most species studied here from previous interferometric maps, albeit at lower angular resolution (see [@gue1997] 1997 and references therein).

The higher angular resolution of the ALMA observations presented here reveals that in fact the broad, 5-10$''$ wide, hollow shell consists of several clumpy thinner shells of width 1-2$''$, which are not fully concentric, as indicated by the arcs which cross each other and by a spiral-like structure seen in the $\sim$1$''$ resolution maps of Fig. \[fig:map\_all\]. This type of substructure was seen earlier in IRC+10216 at larger scales in light scattered by dust grains ([@mau1999] 1999; [@lea2006] 2006) and in emission from CO ([@cer2015] 2015), and has been interpreted in terms of episodic or discontinuous mass loss owing to the presence of a binary companion ([@cer2015] 2015). Observations carried out with the VLA at an angular resolution of $\sim$2-3$''$ also showed that the cm-wavelength emission of HC$_3$N and HC$_5$N consists of clumpy shells consistent with a non-isotropic and episodic mass loss process ([@din2008] 2008). More recently, high angular resolution ALMA observations of the emission in different molecular lines have also provided hints of 