ILLUSTRATIONS 



Plate I 



Fig. 1. In upper left hand corner, a crab cutting out a piece of sponge. 



2. The cutting completed. 



3. The crab has pushed its way under the newly separated piece of 



sponge. 



4. The piece is being carried away. 



TEXT FIGURES 



Fig. 1. Cryptodromia tuberculata Stimpson and its cover. 



2. Alga-tube of Alpheus pachychirus Stimpson. Outline sketch show- 



ing branches and openings. 



3. A diagrammatic view of Alpheus pachychirus Stimpson sewing the 



edges of an alga-mat together. 



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