XV. 



THE NATURAL HISTORY OF 

 AI LSA CRAIG. 



By John Smith, John Paterson, and Hugh Boyd Watt. 



This account of the natural history of Ailsa Craig is based upon 

 contributions made to the Proceedings of our Society (as detailed 

 in Appendix A), and upon observations and experiences of the 

 writers. Mr. Smith is the author of the sections upon Geology 

 and Phanerogams, Mr. Paterson of that upon Birds, and Mr. Watt 

 is responsible for the other subjects, in some of which, particularly 

 with the Invertebrates and Diatoms, he is entirely indebted to the 

 gentlemen named as authorities for the lists. Mr. Watt takes this 

 opportunity of thanking all who have assisted with this monograph; 

 and he believes that, taken along with the information contained 

 in the annotated references named in Appendix B, the reader has 

 now placed at his disposal practically all that is known about the 

 natural history of Ailsa. References are made to the Appendices 

 in an abbreviated form ; — thus A.I is a reference to the first entry 

 in Appendix A, and B.I, 10 is a reference to page 10 of the first 

 work mentioned in Appendix B. 



PHYSIOGRAPHY. 

 Geography and Topography. — Ailsa is situated in latitude 

 55° 15' N. and longtitude 5 6' W., and measures, according to the 

 Ordnance Survey, 3900 feet in length, 2600 feet in breadth, and 

 1 1 14 feet in height. According to the current Admiralty Chart 

 the height, however, is only 1097 feet. It has an area of 220 

 acres, and in circumference is rather more than 2 \ miles ; the tide 

 rising and covering the rough rocky shore, makes a circuit of the 

 island on foot possible only about low water. Girvan is the 

 nearest port, 9^ miles distant, and Ardwell Point, Ayrshire, the 

 nearest land, 8J miles away. It is in the barony of Knockgarron 



