THE HABITS OF SOME TROPICAL CRUSTACEA 



By R P. CowLES 



(From the Zoological Laboratory, University of the Philippines, 



Manila, P. I.) 



One plate and 3 text figures 



On the northern shore of the Island of Mindoro in the Philip- 

 pine Islands lies the almost land-locked bay of Port Galera, long 

 famous for its beautiful "sea-gardens" and for the fact that it 

 affords perfect safety for ships during typhoon weather. On 

 the shores of this bay the University of the Philippines and the 

 Bureau of Science established a temporary marine biological 

 station which was in session during the months of March, April, 

 May, and June of the year 1912. Here during this period I 

 observed the habits of two well-known, peculiar marine Crustacea. 

 The results of these observations are given below. 



SPONGE CARRYING OF CRYPTODROMIA 



Among the many remarkable animals which may be found 

 in Port Galera Bay are the brachyuran crustaceans belonging to 

 the family Dromiidae. The crabs of this family are of special 

 interest because of their supposed primitive characters and be- 

 cause of the fact that some of the species carry pieces of foreign 

 matter over their backs. These covers are usually held loosely 

 by means of the dorsally placed fifth pair of legs, but in some 

 cases they become firmly attached to the carapace. 



Cryptodromia tuberculata Stimpson, the most abundantly rep- 

 resented species of the Dromiidse in Port Galera Bay, lives on 

 the underside of rocks in about the middle of the littoral zone, 

 but it is easily overlooked because it is usually covered dorsally 

 by a little piece of grayish sponge which it carries in the char- 

 acteristic manner of the family. The protection afforded by 

 this cover is further increased by the fact that there are as a 

 rule other pieces of similar shape and size and even larger sheets 

 of the same gray sponge, 4 or 5 millimeters thick and from 300 

 to 400 square centimeters in area, found living independently of 

 the crab and adhering to the underside of the rock. 



It is a surprise to the collector when, on turning over a rock 

 covered with large and small patches of the gray sponge, he sees 



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