394 Dr. Mac Culloch on the Geology of 



constitute a class of rocks entirely different, have been evidently 

 formed together v^^ith the rocks which they accompany, and are, 

 like them, referable to the same epoch, never intruding to their 

 disturbance, but occupying situations and maintaining characters, 

 in every respect conformable to them. It v^^ould tend to the accuracy 

 of geological language, if they were to receive designations derived 

 from their simple parent, hornblende rock, and it is to i)e desired 

 that the occasional mixture of felspar with hornblende, whether that 

 rock be massive or slaty, should be designated by a term, if it 

 requires a distinct one, derived from its true basis, so as to prevent 

 the confusion which their present names introduce into our ideas 

 and descriptions. 



Shiant, 



The Shiant isles having escaped the notice of mineralogists, I 

 shall make no apology for giving such a cursory description of 

 them as my opportunities of observation allowed me to draw up, 

 for the purpose of explaining the specimens which I have trans- 

 mitted. 



These islands are situated to the north of Ruhunish point, in 

 Sky, from which they are distant about 15 miles, and they lie 

 about 8 miles nearly south-east of the entrance of Loch Brolum, 

 in Lewis. There are three principal islands, forming a nearly equi- 

 lateral triangle, besides a few subordinate rocks of considerable 

 height, but of small superficial dimensions. The names of the 

 three largest are Garivellan, Eilanakily, and Eilan Wirrey. Of 

 these the two former are about a mile and half in circumference, and 

 the latter appears to be less than a mile. They constitute one farm, 

 the house appertaining to which is situated on Eilanakily. In ap- 



