An arc of calcium burning in hydrogen at low pressure emits numerous bands in the region 6000-7000A. This spectrum was photographed at high dispersion and two groups of bands, shading toward the violet may be distinguished: the A groups with heads at $\ensuremath{\lambda}\ensuremath{\lambda}7035$, 7028, 6921, 6903 and the B groups with heads at $\ensuremath{\lambda}\ensuremath{\lambda}6389$, 6382. In addition to these, the arc emits an isolated C group---a single band in the ultra-violet at $\ensuremath{\lambda}3533.6$. This group is identical with a band of calcium hydride recently studied by R. S. Mulliken. The structures of A, B and C are very different. The A group forms a doublet system (${\mathrm{A}}_{1}$, ${\mathrm{A}}_{2}$) of $P\ensuremath{-}Q\ensuremath{-}R$ branches. The bands of the B group have a similar structure to that of the violet cyanogen bands, signified by doublet ${P}_{1}$, ${P}_{2}$ and ${R}_{1}$, ${R}_{2}$ branches. The C group consists of a single band having $P\ensuremath{-}R$ branches. In all bands the series deviate largely from polynomials of second degree. Thus, in B and C there is a remarkable "red-shift" of high numbered lines, accompanied by a sharp cut-off in their intensity. From combinations found between the $P\ensuremath{-}R$ branches, conclusions are reached regarding the spectral terms in CaH. The A, B and C groups have a common final ($N$) electronic term with a rotational doubling (${\ensuremath{\epsilon}}_{2}=\ifmmode\pm\else\textpm\fi{}\frac{1}{2}$, ${\ensuremath{\sigma}}_{2}=0$). The initial state of A forms an electronic doublet (${\mathrm{A}}_{1}$, ${\mathrm{A}}_{2}$) with the emission electron in a $\ensuremath{\sigma}$-orbit (${\ensuremath{\epsilon}}_{1}=0$, ${\ensuremath{\sigma}}_{1}>0$), thus explaining the appearance of $Q$ branches in A. In B (initial) there is again a rotational doubling (${\ensuremath{\epsilon}}_{1}=\ifmmode\pm\else\textpm\fi{}\frac{1}{2}$, $\ensuremath{\sigma}=0$). In C (initial) only one $\ensuremath{\epsilon}$ component is present (${\ensuremath{\epsilon}}_{1}=\ensuremath{-}\frac{1}{2}$, ${\ensuremath{\sigma}}_{1}=0$). The departure from half-integral quantum numbers in C is avoided by accepting a large Kratzer's linear term $2\ensuremath{\delta}j$. The nuclear spacings in the CaH molecule are not in correlation with their vibration frequencies, violating a rule by Birge and Mecke. A comparison of the A group with the spectra of ZnH, CdH and HgH shows several interesting parallels, confirming the theory of Mulliken regarding these spectra.