  We study lower-dimensional superstrings in the double-spinor formalism
introduced by Aisaka and Kazama. These superstrings can be consistently
quantized and are equivalent to the lower-dimensional pure-spinor superstrings
proposed by Grassi and Wyllard. The unexpected physical spectrum of the
pure-spinor superstrings may thus be regarded as a manifestation of
noncriticality. We also discuss how to couple these covariant superstrings to
the compactified degrees of freedom described by the N=2 superconformal field
theory.
