APPENDIX. 215 



be ranked with the barrier class, and I have coloured them 

 pale blue. In Lieut. Elmer's chart there is a horse-shoe- 

 formed shoal, laid down thirteen miles N.W. of Pelew, 

 with fifteen fathoms within the reef, and some dry banks 

 on it; coloured dark blue. — Spanish^ Martires, Sanserot, 

 Pulo Anna y and Mariere Islands are not coloured, because 

 I know nothing about them, excepting that according to 

 Krusenstern, the second, third, and fourth mentioned, are 

 low, placed on coral-reefs, and therefore, perhaps, contain 

 lagoons ; but Pulo Mariere is a little higher. 



Mariana Archipelago, or Ladrones. — Guahan. 

 Almost the whole of this island is fringed by reefs, which 

 extend in most parts about a third of a mile from the land. 

 Even where the reefs are most extensive, the water within 

 them is shallow. In several parts there is a navigable 

 channel for boats and canoes within the reefs. In 

 Freycinet's Hydrog. Mem. there is an account of these reefs, 

 and in the atlas, a map on a large scale ; coloured red. — 

 Rota. " L'ile est presque entierement entourde des re'cifs" 

 (p. 212, Freycinet's Hydrog. Mem.). These reefs project 

 about a quarter of a mile from the shore ; coloured red. — 

 Tinian. The eastern coast is precipitous, and is without reefs; 

 but the western side is fringed like the last island ; coloured 

 red. — Saypan. The N.E. coast, and likewise the western 

 shores appear to be fringed ; but there is a great, irregular 

 horn-like reef projecting far from this side ; coloured red. 

 — Farallon de Medinilla appears so regularly and closely 

 fringed in Freycinet's charts, that I have ventured to 

 colour it red, although nothing is said about reefs in the 

 Hydrographical Memoir. The several islands which form 

 the northern part of the group are volcanic (with the 

 exception perhaps of Torres, which resembles in form the 

 madreporitic island of Medinilla), and appear to be without 



