Murray, George W.: An English-Nubian comparative dictionary (London [u.a.]: H. Milford, Oxford University Press, 1923)

xxii Nubian Phonology
letter as an initial is rather remarkable, as it appears in that position in Shilluk
and Dinka as well as in the Bari-Masai group. Bagirmi and Zaghawa, agree with
Nubian in omitting r from the commencement of a word.
Terminally, 1 and r are common Nubian suffixes ; indeed -X was the sign of
the nominative case in Old Nubian. But this suffixed 1 has now disappeared ; and
the participial 1, probably the same suffix, has also gone in the Mahass dialect,
though it is retained in KD. This tendency of final 1 to disappear has affected such
roots as ag, kam, knb which were originally agl, kaml, kubl, &c. The common
nominal suffix -r is also frequently elided.

1, n, and r all interchange in the Nubian dialects, and we get:

mal-ti
KD.
canal
mar-ti
M., cf. mantiti Birked
turb-al
D.
peasant
tiirb-ar
K.
gorban
D.
testicle
gorbar
K.
kal-e
KD.
wedding present
kan-e
M.

More remarkable is the occasional
even h, thus :

interchange of r and n before g, h, or

orgo
Dai.
day
ohg-i KD.
orn-do
Dai.
star
ongye-di Mid.
kirgisse
K.
thorn
kinisse K. (Here kinisse probably = kifiisse s.p. 102)
magise
K.
grass
mahissi M. (Here magise probably = margise s. p. 118)
digri
KD.
many
diyi M. (for dini ?)

Examples have already been given in 4 of the interchange of 1 and r with d ;
and additional instances may be found in the terminal letter -r of the personal
pronouns, and the initial r of the personal-endings of the present tense. These
frequently change to d, e. g. when the personal pronoun ter is followed by a suffix
with initial r, we get d-d instead of r-r, thus ted-de D., ted-do KD. for ter-re,
ter-ro. So, after a verbal root with terminal n, we get ai an-di, ban-di, gen-di
for ai an-ri, ban-ri, gen-ri, &c. Similarly the suffixed -r, which intensifies the
verbal root, does the same thing in sugud, nodd for sugur-d, nor-d for sugur-r,
nor-r from roots sugur descend, nor be cut.