of Mississippi and Louisiana 67 



the amount of moisture in the sand varies with its elevation above 

 tide and the greatest variety in flora is found on the largest islands 

 having the greatest variety of soil and elevation. 



3. The Mud Lumps. — The mud lumps vary in size from a few 

 square rods to perhaps fifty acres. The general surface is some- 

 what undulating, and from one to three meters above tide. The 

 soil is very compact, black or yellowish, with almost the texture 

 of joint clay. None of these islands showed any of the usual 

 signs of growth on any side, while all appear to be wearing slowly 

 from wave action. 



The contiguous waters are very shallow and the amount of 

 salt held in suspension is considerable, decreasing as one passes 

 seaward. The algal vegetation is small, even in the most favor- 

 able locality visited, Breton Island, and is to be found chiefly in 

 the lee of the island. The collection has not yet been studied, 

 and remains to be reported upon later. 



Such extensive shallow waters, especially in the lee of an 

 island, favor the extensive growth of Ruppia, with, however, 

 scarcely any other plant save the few algae. 



The Plant Covering 



Any attempt to present an analysis of the floral covering of the 

 region just briefly described must of necessity be more or less un- 

 satisfactory, for an analysis attempts to present the conditions as 

 they are, while in point of effect we are dealing with a series of 

 changes in those conditions. It must be admitted also that but 

 w Plants are habitually confined to one association, or even for- 

 mation, and to delimit these is often no easy task, involving 

 much more time in the field than the writers have had at their 

 disposal. The following account may be claimed to be a fairly 

 true picture of the conditions described, but would probably need 



as 



Beach fc 



Sand Strand Vegetation 



ormati on. 



Lower beach : no vegetation. 



Middle beach. 



Upper beach : Panicum amarum association. 



