On Foyaite. 153 



Secondly, that Upper Keuper deposits are alone represented in 

 Normandy. 



Thirdly, that fragments of the Palaeozoic rocks of what is now 

 Normandy were never incorporated in the Triassic rocks of Devon. 



Fourthly, that the constitution of the coasts of Normandy, Devon, 

 and Cornwall is such as to justify a belief that varieties of 

 Cambrian, Silurian, Devonian, and Granitic rocks formed the bed of 

 the Triassic waters in the area now occupied by the English 

 Channel, and that to these sources fragments foreign to the Devon- 

 shire soil found in the Triassic beds on the South-Devon coast are 

 to be attributed. 



4. " On Eoyaite, an Elaeolitic Syenite occurring in Portugal." 

 By C. P. Sheibner, Esq., Ph.D., E.G.S. Communicated by Prof. T. 

 M'Kenny Hughes, M.A., E.G.S. 



The name foyaite is derived from Mount Eoya, in the south of 

 Portugal. This rock occurs intrusive in Devonian grauwacke in 

 the ancient province of Algarve, where it forms two dome-shaped 

 hills, the Eoya and the Picota, rising respectively to 2968 feet and 

 2410 feet. The texture of the rock varies from fine- to coarse- 

 grained, and is sometimes porphyritic. An almost compact variety 

 occurs cutting the coarser rock in dykes and veins. The coarser rock 

 occurs mainly on the southern slopes, where, however, the adjoining 

 grauwacke is less altered than elsewhere. The massif is also cut by 

 intrusive veins of phonolite and basalt of Tertiary age. Much rock 

 has probably been removed from the district by denudation. 



Macros copically foyaite consists of orthoclase, elseolite, and 

 greenish hornblende. Orthoclase with imbedded eleeolite occurs 

 porphyritically. A lens shows titanite, biotite, magnetite, and 

 pyrite to be accessories. Microscopically examined, the above con- 

 stituents are seen to be present, and exhibit considerable variety in 

 their mode of occurrence, together with nosean and sodalite as 

 characteristic accessories, and occasional plagioclase (recognized as 

 oligoclase), muscovite, haematite, and apatite. The elaeolite is irre- 

 gular in outline; nosean and sodalite are often associated with and 

 imbedded in it. The latter minerals are associated and intergrown. 

 Their mode of occurrence and the tests for their presence are 

 described in detail. Hornblende and augite occur in foyaite in 

 about equal quantities, associated and intergrown. These also are 

 fully described, as well as the characteristics of the other accessories. 

 Analyses of the elaeolite and the foyaite are given. The author 

 concludes by pointing out the close resemblance of the rock to 

 ditroite, miascite, and certain syenites of Brevig and Cape Yerd, 

 stating that on this account there is no need of a special group of 



