Distribution in Panama (Description, San Bias). 



The San Bias Islands begin at Punta San Bias, a point 100 kilometers 

 Northeast of the City of Colon, It arches parallel and less than 20 kilo- 

 meters from the Caribbean coast of Panama in a Southeasterly direction for 

 about 160 kilometers to Punta Escoces near the border with Colombia. 



The Archipelago is formed by several island groups, each separated 



from the other by deep channels . The outer groups, those facing the open 



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sea, are protected by a well developed algal reef formed by e-rus-tecea 

 coralline algae and vermetid gastropods (Glynn, 1973) . The area between 

 the algal reef and the Islands is a vast shallow flat of sand and turtle 

 grass, Thalassia testudinum with sparcely scattered heads of coral. The 

 islands and cays are located at the leeward end of the sand flats. The 

 islands' leeward side is a steep, sometimes vertical, face of firm strata 

 formed by hard luxuriant corals to depths varying from 5 to 30 meters. 



The inner islands, devoid of an immediate algal reef, are structured 

 similarly except that their steep coral face is on the seaward side and 

 the shallow sand flats usually occur on the side facing the mainland. 

 Each island is surrounded by patches of sand shallows and T. Testudinum 

 flats on one side and fringing coral reefs that drop sharply to a bottom 

 of coral rubble and sand to depths of 5 to 30 meters. 



All field observations and pertinent data were gathered in the San 

 Bias Archipelago. However , in order to verify the occurrence of the 

 species throughout the Caribbean coast of Panama, eleven stations were 

 examined starting at the San Bias Islands and extending to Almirante Bay 

 in Bocas del Toro province, bordering with Costa Rica. S. sepioidea was 

 evident in all stations. 



