It is difficult to trace any rational origin for this name, which is found in the treatises of both Quantz (1752) and J.F. Agricola (1757).  See Scotch Snap."

"Scotch Snap

     A melodic figuration consisting of a stressed semiquaver followed by an unstressed dotted quaver, usually applied to melodies that fall or rise by steps. It was current in European art music between 1680 and 1800, and in Scottish strathspeys from 1760 to the present day. Its origins are obscure. In Italy it was regarded as a Lombard characteristic; in France it was called the manière lombarde. Quantz (Versuch, 1753) wrote: 'This style began [in Italy] about 1722, but it seems to resemble Scottish music'. Burney, writing of Italian Opera in London in 1748, deprecated the over-use of the 'Scots catch or cutting short of the first of two notes of a melody'...

These comparisons imply that Scottish dance music was performed with Scotch snaps many years before the first printed strathspeys appeared in the 1760s. The art sonatas of the Scottish composers James Oswald (Airs for the Four Seasons, 1755) and John Reid (flute sonatas, 1762) show an interesting confluence of the Italian and Scottish traditions.

But Purcell was using Scotch snaps long before Quantz's source-date of 1722. None appeared in his earliest works, but they are well established in the coronation Anthem
My Heart is Inditing (1685). Purcell's source for the figure may have been the French Notes Inégales or alternatively Scottish folksong: both French and Scottish music were in vogue in London in the 1680s. In his song Twas within a furlong of Edinborough town (1694) the figure has Rustic overtones; elsewhere (e.g. the recitative leading to 'When I am laid in earth', Dido and Aeneas, (1689) it is associated with elegance and passion.

In Handel (e.g. Musette of Concerto Grosso op. 6 no. 6, 1739) and other British composers of the mid-18th century, the figure has exclusively rustic or naïve associations. The same is generally true of its appearances in the work of Mozart (several serenades and string quartets) and Beethoven (finale of the Serenade Op. 25).

After 1800 art music melodies became concerned with Romantic expressiveness at the expense of speech-rhythm: at this point composers lost interest in the Scotch snap. It has continued, however, as one of the main figurations of Scottish dance music, and has occasionally been used for its Caledonian flavour by such later composers as Mackenzie, MacCunn and F. G. Scott ..."           David Johnson

From The Illustrated Encyclopedia of Music:

"Scotch Snap (or Scots Catch)

     A form of rhythm in which a short note on the beat is followed by a longer one that lasts until the next beat (e.g. Coming Through the Rye and in the Strathspey). It was also popular in Italy in the 17th and 18th centuries and was known in Europe as the Lombardy Rhythm".

The section on Lombardic Rhythm begins on Page 58 of
"Folksongs for the Violin", Part 2 : The Violin in Major Keys
(A Graded Selection of Melodies for Beginners of All Ages).

Details on the MUSIC PAGE

A: Lombardy…the Lombards…Germanic 6th Century conquerors of Italy.

The Lombards (or Langobards = Long Beards) were a Germanic tribe that migrated from Sweden to Northern Italy, over the course of 400 years, arriving in Italy between 568 and 572, and giving their name to the region of Italy known as Lombardy.

In 572 the Lombard chief, Alboin, founded the Kingdom of Lombardy. The Lombards eventually became Italian, spoke the local language, and converted to Christianity. The Lombard dynasties continued until 774, when they were overthrown by the Frankish king, Charlmagne.

Lombardy

Region in North Italy comprising the provinces of: Bergamo, Brescia, Como, Cremona, Mantua, Milan, Pavia, Sondria and Varese. Milan is the regional capital. Ancient Lombardy, known as Cisalpine Gaul, was a part of the Roman Empire in the 3rd century BC. From the 6th to the 8th centuries AD, the area was ruled by the Lombards. By the mid 15th century the city-state had become a duchy. Lombardy was ruled successively by Spain, Austria, France, and Sardinia, and became part of the Kingdom of Italy in 1861.

Lombard League

In March 1167, the cities of Cremona, Mantua, Bergamo and Brescia formed a military alliance against the Holy Roman Emperor Frederick I (Frederick Barbarossa {=Red Beard}), known as the Lombard League. Parma, Padua, Milan, Verona, Piacenzo, and Bologna later joined the league, which was victorious against Frederic Barbarossa in 1176. The battle was the first occasion on which feudal cavalry (the basic military organization of the nobility) was defeated by infantry (the basic military organization of the towns). The League, reactivated in 1226 against Frederic II, grandson of Frederic Barbarossa was defeated in 1237.