52 BULLETIN : MUSEUM OF COMPAKATIVE ZOOLOGY. 



plants so characteristic of the shore lines of all the Bahamas. Upon 

 these sand ridges also flourished small groves of palmettos. 1 



As we steamed northward, the low, dark line of Audros stood out in 

 marked contrast with the intensely light-green water, extending as far as 

 the eye could reach over the shallow bank to the westward of the island. 

 Here and there the low line was broken by a high mangrove tree loom- 

 ing up like a cliff in the distance, or was interrupted by a stray line of 

 high palmettos on some sand ridge near the shore. The edge of the 

 island near Wide Opening is occupied by a lagoon inside the shore 

 line, and the deep bights which characterize the island show clearly 

 how it has little by little been eroded, then cut into halves and 

 thirds, next into smaller cays, and finally, wearing away having com- 

 menced, has left here and there a small cay (Plate XII. Fig. 3, and 

 U. S. Hydrographical Chart, No. 26 a ) to the westward of the main 

 island. As the water is quite shallow all along the west shore of An- 

 dros, its action is most feeble, and it must have triturated and ground 

 very slowly all the shore material into the very fine and minute particles 

 composing the " white marl " covering so large an area of the bank be- 

 tween the island and the Santaren Channel. This white marl looks 

 almost like deep-sea chalky ooze ; it has about the same consistency, is 

 made up of the same nearly impalpable fine particles, and is of the same 

 whitish color. A similar white marl deposit is also found, only on a most 

 limited scale, in protected pools exposed to the very lightest wash of the 

 sea in the recesses of the shore line. 



The shores of the inner lagoons, and in many places the main shore 

 of the island, is lined with mangroves, many of which are large, and form 

 the most prominent landmarks available in the navigation off the west 

 shore of Andros. 



As far as Williams Island, about twenty-five miles to the northwest of 

 Wide Opening, the bottom on the bank is composed of the same white 

 marl. All the way to Billy Island we found no change in the character 

 of the bottom, which seemed fully as barren of animal life as it proved 

 while rowing to the shore of Wide Opening from our anchorage. On 

 our way north from Wide Opening we steamed in water so shallow that 

 we left in our wake a broad belt of white water, stirring up the white 

 marl with the wash of the screw. 



On going ashore at Billy Island we found it to consist of the same 

 finely triturated seolian rocks. The shores were formed by miniature 



1 See Northrop's description of the " Swash " (" The West Coast of Andros," 

 Trans. N. Y. Acad, of Sci., Oct., 1890). 



