"Eclipsis (is the) mutation of consonants from unvoiced to voiced following a nasal" . (Alexander 1952).  The SGDS deals, for the most part with single words and so there is therefore limited scope for examining any spatial differences of this feature, in the Gaelic of the Scottish Highlands.  There are, however, three examples and diffences in eclipsis have been plotted on the adjacent maps. 

The examples are :

Ceann-tIre, seann-tè and an-dè.

In the first two, the eclipsis is seen with 't' (sounding like tshay) replaced by 'd' (sounding like dzhay) in many cases.  There is a difference in the distributions, even although they are of the same form of eclipsis, with, in the case of 'seann-tè' the eclipsis found much more strongly in the west, with the main exceptions of Sutherland and Lewis. With 'ceann-tìre', the east-west split is much less marked, with eclipsis mainly in western Inverness-shire.

In the case od 'an-dè', the voiced stop 'd' can be eclipsed to sound as 'n', so that 'an-dè' can change for 'an-jay' to 'an-yay'.  This distribution is limited to western Sutherland, Lewis and parts of Skye.

Alexander (1952 p. xx) points out that eclipsis is to found conserved in Scottish places names in Aberdeenshire.  No doubt that this is true over much of the rest of Scotland as well!

Names such as Birse (am preas - with metathesis = 'the bush'), Bedagleroch (bad nan clèireach= 'hamlet of the clerics'), Achnagorth (ach nan coirthe = 'field of the standing-stones') Feindallacher (fèith an t-salachair = 'muddy burn') all show eclipsis.