102 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



Navidad, Silver, and Mouckoir Banks. 



Plate IX. Figs. 7, 8, 10. 



The most southerly of the Bahama banks is Navidad Bank. It has 

 a least depth of eleven fathoms near the southeastern extremity. From 

 the soundings it appears to vary little in depth. The southeastern part 

 of the bank slopes off to the 100 fathom line somewhat less abruptly 

 than either the eastern or western face. The depth on the main body 

 of the bank varies from eleven to seventeen fathoms. It is covered with 

 aeolian sand modified by Nullipores. Navidad Bank is oval-shaped, 

 twenty-two miles long in a north and south direction, and in the centre 

 about eleven miles wide. 



Between Navidad and Silver Banks there are three small submarine 

 banks rising to a depth of ten, twelve, and seventeen fathoms. 



Silver Bank, the next bank to the westward, is an irregularly rectan- 

 gular bank. Its eastern somewhat concave side is twenty-nine miles 

 long. The northern side is thirty-eight miles. The central part of that 

 side, at a distance of about eight miles from the southeastern extremity, 

 is occupied by a triangular patch of coral heads which are awash and 

 extend nearly five miles inland, towards the northwest angle of the 

 bank. 



The west side of the bank runs nearly north and south thirty-seven 

 miles. Coral heads ci'op out only at one point of this side of the bank, 

 and also on the western part of the southern line of the bank, which is 

 twenty-four miles long. 



The soundings on the bank vary from six to twenty fathoms. The 

 deeper soundings occur nearer the western side of the bank. 



The last of the larger submerged banks is Mouchoir Bank, the outline 

 of which is more irregular than that of Silver Bank. Its greatest length 

 from east to west is about thirty-one miles. Its breadth north and 

 south varies greatly. The eastern face is twenty-five miles, extending 

 into a long narrow spit. The depth on the bank varies from seven to 

 fifteen fathoms. On the north side there are two large patches of coral 

 heads awash, both extending some distance south on the bank. 



From what I can learn, the coral heads on Mouchoir and Silver 

 Banks are growing upon pinnacles of aeolian rock. 



