  We review the physics underlying Meyer's conjecture of how macroscopic-scale
twist and bend conspire within the Frank-Oseen elasticity theory of nematics to
create a heliconical arrangement of the uniaxial, apolar nematic director, the
so-called "twist bend nematic" $\rm N_{TB}$. We show that since 2011 a second,
lower-temperature nematic phase observed in odd methylene-linked cyanobiphenyl
dimers discovered by Toriumi and called $\rm N_X$, has been incorrectly
identified as $\rm N_{TB}$. Moreover, as more quantitative data on the $\rm
N_X$ emerged, Meyer's simple prediction has been distorted to accommodate those
findings. In fact, the molecular organization in the $\rm N_X$ conforms to the
$\rm N_{PT}$ phase, a polar, twisted arrangement of nonlinear mesogens advanced
in 2016. The attributes of the $\rm N_{PT}$ are summarized and differentiated
from those of the $\rm N_{TB}$ in an effort to contribute to a better
understanding of the $\rm N_X$ phase and, equally important, to encourage
researchers to continue to search for a liquid crystal that exhibits Meyer's
pioneering theoretical suggestion, namely that form-chirality can exist in
simple nematics composed of achiral molecules.
