Vol.51.] OF A JOURNEY IN MADAGASCAR. 63 



abundant epidote are also found in the neighbourhood of lat. 

 13° 17' S.j a mile or two from the sea. 



In one or two localities occur considerable areas of granitite 

 (biotite-granite), as, for instance, in the neighbourhood of Vohija- 

 nahary (lat. 16° 10' S.), the capital of the Mananara province. 

 Another extensive area, but of unknown limits, north of Antongil 

 Bay, in the neighbourhood of long. 50° E., lat. 15° 20' S., taken as 

 a central point, consists, for the most part, also of granitite. All 

 the slides taken from the rock of this locality show under the 

 microscope that it has been subjected to much mechanical dis- 

 turbance, the structure being that known as cataclastic. The rock 

 has here been very extensively invaded in all directions by dykes 

 and bosses of epidiorite (387) ; this is especially the case some 8 or 

 10 miles north of the head of Antongil Bay (in the neighbourhood 

 of the village of Eizony) ; but epidiorite also occurs now and then 

 in dykes as far south as lat. 12° S. and as far north as lat. 13° 15', 

 where it forms fairly high hills (463). The epidiorite occasionally 

 shows spheroidal weathering. In one locality (about long. 50° 10' E., 

 lat. 15° 5' S.) 1 found in the bed of the River Sahafihitra numerous 

 blocks of chiastolite-slate and argillaceous schist, but I nowhere met 

 with these in situ. Quartzite occurs also in various localities in the 

 neighbourhood of this granitic area. Of the precise field-relations 

 of these rocks I cannot, I am sorry to say, give any particulars, 

 having crossed the area only in one direction, and that somewhat 

 hurriedly ; but that the granitite is eruptive seems to be indicated 

 by the existence of the chiastolite-slate, and also, not improbably, by 

 the quartzite. 



Aplite occurs also in considerable quantity in various localities, as 

 2 or 3 miles north of Manompana (lat. 16° 43' S.), at Manambato 

 (lat. 16° 33' S.), at Manakambahiny (long. 49° 43' E., lat. 15° 8' S.), 

 and at Ampanobe, 2 or 3 miles from the sea (lat. 13° 40' S.). 



Other rocks found on this eastern coast-line are : — 



Hornblende-schist (263) (pro- Three miles north of the village of 

 bably much altered epi- Andranovola in Antongil Bay ; 

 diorite). 4 or 5 miles south of Soanierana, 



at the head of Antongil Bay (269, 

 270) ; and also in the neighbour- 

 hood of the village of Sahaka, 

 opposite the island of Ste. Marie. 

 Augitic quartz-diorite (312) . Village of Sahaka, opposite the island 



of Ste. Marie. 

 Mica-schist, crowded with Soamianina, opposite the island of 

 crystals of blue kyanite, Ste. Marie ; and also several miles 

 often a couple of inches in south of it. 

 length. 



Norite (374, 375) Three or four miles north of the 



village of Antanambe (lat. 12° 25'); 

 and a little south of the village 

 of Tanjona, in Antongil Bay. 



