Z(gh) | Z(dh) | v,w(bh) | v,w(mh) |
+--------+---------+-------+-------+-------+-------+---------+---------+
| Welsh | g | d | b | nil | d(dd) | v(f) | v(f) |
+--------+---------+-------+-------+-------+-------+---------+---------+

2. When the word causing mutation originally ended in a nasal, we get
the nasal mutation called by Irish grammarians eclipse. The sounds
affected are k (c), t, p; g, d, b; Prim. Celt. v (Ir. f, W. gw). In
mod. Irish and mod. Welsh the results are tabulated below. Irish f
becomes w written bh, whilst W. gw gives _ngw_. Examples:--Irish
_bliadhna_, "year," _seacht m-bliadhna_, "seven years," cf. Latin
_septem_, Welsh _blynedd, saith mlynedd_; Irish _tir_, "country," _i
d-tir_, "in a country," Welsh _tref_, "town," _yn nhref_, "in a
town," cf. Latin _in._

+----------------+-----+-----+-----+-----+-----+-----+
| Original Sound | k | t | p | g | d | b |
+----------------+-----+-----+-----+-----+-----+-----+
| Irish | g | d | b | ng | n | m |
+----------------+-----+-----+-----+-----+-----+-----+
| Welsh | ngh | nh | mh | ng | n | m |
+----------------+-----+-----+-----+-----+-----+-----+

3. In Welsh k (c), t, p undergo a further change when the word causing
mutation originally ended in s. There is nothing corresponding to this
consonantal mutation in Goidelic. In this case k (c), t, p become the
spirants [chi] (ch), th, f (ph), e.g. _lad_, "father," _ei thad_, "her
father," ei represents a primitive _*esias._ In the interior of words
in Brythonic, cc, pp, tt give the same result as initial k, t, p by
this mutation.

The relation in which the other Celtic dialects stand to this system
will be mentioned below in dealing with the various languages. It will
be noted from what has been said above that, with the exception of the
different treatment of the labialized velar qv, and the nasal sonant n,
the features which differentiate the Brythonic from the Goidelic
dialects first appear for the most part after the Romans had left
Britain. At the beginning of the Christian era the difference between
the two groups can only have been very slight. And Strachan has shown
recently that Old Irish and Old Welsh agree in a very striking manner in
the use of the verbal particle ro and in other syntactical peculiarities
connected with the verb.

(i.) _Goidelic_.--T