British Guiana 4d Listing Question

Can anyone give a definitive listing for the 4d coins issued by British Guiana? Also, when did they change from 925 silver to 500 silver?

I have one reference which only gives snapshots of lists (not much help). My other reference claims to be definitive, but makes no mention of a 1910 issue. When I found one from 1910 this reference lost some credibility.

As far as I understand it they were issued from 1891 to 1945, with some gaps. I think they changed to 500 silver in 1944 but am not certain.

I am trying to collect the full set. So far I have:
1891, 1894, 1910, 1911, 1917, 1918, 1926, 1936, 1938, 1942, 1944.

The 1891 reverse legend is "BRITISH GUIANA & WEST INDIES". From my 1917 coin onwards it just says "BRITISH GUIANA". In what year did it change?

Thanks in advance.