April, 1916. Alacran Reef — Millspaugh 421 



VEGETATION OF ALACRAN REEF 



The Alacran Reef forms the northeastemmost danger on the Cam- 

 peche Bank, in the Gulf of Mexico, 75 miles N. by E. ]4 E. from Sisal 

 Fort on the Yucatan mainland. The position of Perez Cay, its most 

 southern islet, is latitude 22°33'36"N.; longitude 89°4i'45"W. 



The general form of the reef is semilunar, convex to the NE., the 

 straight western face trending NNW. >^ W. 14 miles, its greatest width 

 being 8 miles. The weather, or NE. side, is composed of a compact 

 mass of coral, dry in many places, over which, on all parts, the sea 

 breaks with violence. The lee side, similar to all reefs of this character 

 in these seas, is composed of detached coral heads, easily seen in the 

 clear, deep water of the bank. 



At the SE. extreme of the reef are three small, sandy cays rising 

 not over 5 ft. high. These are known as Perez, Pajaros and Chica Cays. 

 Pajaros and Chica lie yi mile apart 800 yds. from the SE. extremity of 

 the reef, Perez l3dng about a mile westward from them. Between the 

 eastward pair and Perez there is an excellent reef -harbor for small ves- 

 sels; formerly 4 fathoms could be carried into this harbor but at the 

 time of oiur visit it held, in a few places, but a precarious 2 fathoms. 



NW. by N., 3 miles from Perez, is a small cay, about 8 feet high, 

 which we named Allison Island, and about the same distance southward 

 of the NW. end of the reef is another islet, about 10 feet high, which we 

 named Utowana Cay, though we were unable to land upon it on account 

 of sea conditions at the time of our approach. 



The Alacran Bank is everywhere so steep-to that there is no safe 

 anchorage for larger vessels, not even on the lee side, the only clear 

 landing place is on the inner side of Perez Cay at the mouth of the reef- 

 harbor mentioned. 



The approach to this shoal, when working to windward, requires 

 more than ordinary attention as the soundings near it do not give suf- 

 ficient warning and the islets are invisible if the sea be high. As the 

 Yacht Utowana (which the owner and master Mr. AUison V. Armour 

 allowed to approach the reef on the voyage of which I had the honor of 

 being his guest) arrived in the neighborhood, the captain slowed the 

 vessel down and sent a lookout to the cross trees. Though we proved to 

 be but about two miles from Allison Island yet nothing could be seen 

 of the reef until a cloud of frigate-birds* arose indicating its presence. 



As the reef lies directly within the sweep of the Gulf Stream in the 

 youth of its course we judged that it might receive aquavectent seeds 

 *Fregata aquila (Linn.). 



