(7) The maritime plain had its maximum seaward extension after the growth of coral on the second and third barriers. Owing to elevation nothing has been added to its seaward slopes since the formation of the features of the present coast-line by secondary faulting. (8) The filling in of valleys and the completion of the connection of the second barrier with the maritime plain has been largely due to blown sand. The process is continuing, e.g. an extensive plain near Dongonab shews perfect uniformity in its formation. INDEX Acacia bushes, beauty of 3 use 50 Administration by native Shêkhs 27 Akaba 122 Alexandria 111 Amulets 42 Animals resembling seaweed 8 Arabs 15 Archean rocks 127 Arms 23, 27 use of 28 Arûs harbour 148 Association of corals and higher animals 94 with microscopic plants 95 Atbara route to Nile ix district 19 Axum, mediaeval trade route of 39 Baraka flood and delta 151 Benas, Ras 141 Biologist’s justification viii, x Bisharia, tribe 15 Block mountains 125 Boring animals 101 Boundaries of Anglo-Egyptian coast vii Brothers Islets 123 Cape Verde Islands 110 Cats 45 Challenger Society x Clams (_Tridacna_) 69, 100 as food 59 pearls from 69 Climate, Red Sea coast 118 _Clione_, boring sponge 101 Corals, animal nature of 85 cups and polyps 85 colours 93 formation of colonies 89 genera _Caryophyllia_ (British coral) 87, 91 _Dendrophyllia_ 89 _Fungia_ 92 _Galaxea_ 94 _Madrepora_ 91 _Porites_ 89, 100 (see also plates 26 and 28 and explanation p. 88) life-history 98 physiology 86, 95 place in evolution 96 plant-like nutrition 95 sizes of colonies 89, 91 variety of forms 90 Coral Reefs—see Reefs “Coralline” seaweed 100 Crystallisation of coral limestone 111 _Cymodocea_, a marine plant 108 Daedalus shoal 124 Dance, religious 41 Darwin’s theory of atoll formation 114, 136 Delta of the Baraka 151 Depth of Red Sea 121 Destruction of corals 100 Devil fish or sting rays 70 Dhow, or _sambûk_ sailing vessels 59 Diving, as seamanship 63 for pearl oysters 66 Divorce 75 Dongonab Bay 104, 138, 141 reefs in 153 Dongonab plain 155 Dulawa harbour 147 Dunn, Sudan Government Geologist vii Eclipse of the moon 47 Elevation of reefs above sea 131, 133 in Pemba and Zanzibar 109, 110 _Eunice_, marine worm 101 Evil eye 44 Evolution 96 Faulting, geologic term 122 Fijab harbour 148 Fishing 68 Fish spearing 70, 71 Funafuti atoll reef 114 Gardiner, Prof. J. Stanley ix Geologic time 97, 132 Geological history of Red Sea, summary 154 Gordon 14 Gregory, Professor 122, 125 Hamitic natives 16 personality of 22 Harbours, natural 146 Hardihood of natives 30, 54, 78 Honesty 49 Ibrahim’s wife 76 Jebel Abu Shagara and J. Têtâwib 138, 143 Jedda 12, 21