APPENDIX 



479 



of African species (p. 35) it is pointed out that the majority of them 

 are endemic, the only exceptions being ten species that are there 

 named. But unless the student goes through the whole list, there 

 is nothing to indicate, what is actually the fact, that seven of these 

 species are not known from the African continent at all, and only come 

 into the list as components of the Sphagnum flora of the Azores, 

 a group of islands placed here under Africa. All the seven species 

 range widely over the globe, and their inclusion as African would 

 thoroughly change the character of the Sphagnum flora of the con- 

 tinent, especially as concerning its external connections, Africa 

 being almost a closed region as far as the Peat-mosses are concerned. 

 With respect to Sphagnum, the Azores are plainly a part of the 

 European region, there being no African affinity, and no North 

 American connections except such as are also European. 



Note 23 (p. 38). 



Pumice on the beaches of the Azores. 



Pumice is washed up in quantities on Azorean beaches, but 

 doubtless it is almost all of local origin. On the north coast of San 

 Miguel it is very abundant, being evidently brought down in the rainy 

 season by streams from the inland districts. Pumice-tuffs often 

 predominate in the interior, and as a result of their disintegration 

 pumice is strewn over great areas of the surface. The pumice is 

 evidently andesitic, being naturally darkish in colour but presenting 

 a light-coloured, weathered exterior. The fragments are as a rule 

 very buoyant when freshly removed from the tuffs, and no doubt 

 would float for years. (In one of my experiments in the Solomon 

 Islands, referred to in my book on the geology of that group, andesitic 

 pumice pebbles originally gathered in the tow-net at sea remained 

 afloat after two and three-quarter years.) In time, however, pumice 

 lying exposed on the surface in wet localities loses its buoyancy. 

 Thus I found that after being exposed for a long period on the scantily 

 vegetated higher slopes of Pico da Vara in San Miguel, where the 

 rainfall is great, the pumice fragments had become sodden and 

 no longer floated. On the shores of Lake Furnas in the centre of 

 the island they may be seen in a well-rounded state, due to attrition 

 during prolonged flotation in its waters. In that state they are 

 carried down by the effluent streams to the sea. It is therefore 

 necessary to remember that pumice may begin its trans-oceanic 

 voyage in a well-worn condition. 



Note 24 (p. 377). 



Trailing growth of Anagallis tenella. 



A singular variation in growth was displayed in an experiment 

 made in South Devon some years ago. The typical plants are 

 usually described as possessing creeping stems a few inches long 

 (three or four inches). However, in the spring of 1906 I noticed 



