XXVI. — Sketch Map showing Tribal Boundaries 368 XXVII. — Sketch Map of Route from Halaib to Mohamed Ghul 372 XXVIII. — Sketch Map of Route from Mohamed Ghul to Port Sudan 372 LIST OF ILLUSTRATIONS IN THE TEXT. * * * * * FIG. PAGE. 1. Sketch-map showing position of area described 1 2. Map of Abraq Springs 123 3. View from the summit of Gebel Elba 229 4. Granite of Gebel Fereyid 269 5. Red pegmatitic granite of Wadi Gemal 271 6. Biotite-granite of Gebel Abu Hegilig 273 7. Hornblende-granite of Gebel Elba 275 8. Hornblende-granite of Gebel Hamata 275 9. Granite-porphyry of Kreishim Hill 276 10. Quartz-felsite of the Wadi Huluz 277 11. Quartz-felsite from a dyke at Gebel Kolaiqo 278 12. Altered quartz-felsite of Gebel Igli el Iswid 281 13. Microperthitic structure in felspar of quartz-felsite of Gebel Hadarba 282 14. Fractured felspar crystals in crushed quartz-felsite of Wadi Huluz 282 15. Syenite of Gebel Zergat Naam 284 16. Syenite-porphyry of Gebel Zergat Naam 284 17. Trachyte from a dyke at Gebel Kahfa 285 18. Diorite of Gebel Allawi 287 19. Diorite of Wadi Baaneit 287 20. Augite-diorite of Wadi Um Hargal 289 21. Augite-diorite of Gebel el Anbat 290 22. Mica-diorite from a dyke at Gebel Abu Hegilig 291 23. Diorite-porphyrite of Gebel Abu Hodeid 292 24. Augite-porphyrite of Wadi Muelih 293 25. Kersantite of Gebel Fereyid 294 26. View near the top of Gebel Sufra 296 27. Andesite of Gebel Sufra 296 28. Gabbro of Gebel Dahanib 298 29. Gabbro of Um Eleiga 299 30. Hypersthene-gabbro of Hadal Aweib Meisah 300 31. Olivine-gabbro of Gebel Um Bisilla 301 32. Olivine-gabbro of Gebel Atut 302