KiNAHAN — Killary Bay and SUeve Partry Silurian Basin. 711 
rock ; while in other cases the nodular varieties graduate into them. 
The nodular varieties in general have a hornblendic matrix, but not 
always so, as in places the matrix may he felspathic. The schistose 
varieties belong to two distinct classes. If they occur at the upper or 
lower margin of a course of the normal rock, they are evidently a portion 
of the mass that has acquired their foliation from some special cause ; 
but if they occur in continuation of a course, especially if they are 
adjuncts of the nodular varieties, originally they had more or less of a 
sedimentary origin. E'early invariably they contain eyes," and 
graduate longitudinally into other varieties of schist, or into conglo- 
meritic-schists and gneiss, which may be micaceous or felsitic or even 
quartzitico The "eyes" usually are hornblende rock, but often are 
not. 
Some ask us to believe that all these varieties are solely due to 
difference in the shearing process, as the rock, originally, was one 
intrusive mass, and of this, the normal hornblende rock represents the 
untorn-up portion, while the nodular and schistose varieties represent 
the original in different stages of reconstruction. Before, however, 
this is believed, it seems necessary that they should explain how in 
places the matrix of the nodular varieties are micalites, felsilites, or 
even quartzites? and how so many of the ''eyes" in the schistose 
varieties of the second class are of foreign rocks? Also why these 
adjuncts to the normal hornblende rocks have characters so similar to 
those of the adjuncts of whinstones in unmetamorphosed area ? and 
even to the adjuncts of the recent volcanic rocks ? This last question 
we will now demonstrate. 
Z/hmetamorpMc Rochs. — In the Ordivicians of Dublin, Wicklow, 
Wexford, and Waterford,^ the courses of whinstone nearly invariably 
have shaly margins, while often they graduate into nodular varieties, 
and in some places, as can be ocularly proved, an intrude is in part 
a whinstone and in part an agglomerate or tuffoid rock. In the Vol- 
canic, or Bally money series, Co. Wexford, some most interesting changes 
take place, the normal whinstone graduating into a tuffoid rock or 
agglomerate, often calcareous, and thence into shales and limestones. 
^ No correct maps of this district are pubHshed. Jukes condemned the early 
survey, as for the most part it was a rough traverse made by W, "W. Smyth, Dela 
Beach, Oldham, &c., as can be learned from their maps. The portions so loosely 
lurveyed he ordered to be re-surveyed by Du Noyer. The survey and descriptions 
)i the latter were not approved of by Jukes ; but eventually, when pressure was 
mi on him the maps were published ; but they were considered by Dr. Hull to be 
10 incorrect that I was deputed to revise them. My maps were approved of by 
E.I.A. PEOC, SER. III., VOL. I. 31; 
