Krause Lagoon and Limetree Bay on the southern coast were observed 

 but Krause Lagoon was not examined in detail. It is nearly ocmipletely 

 out off from the sea and is reported as being shallow and having an 

 extremely soft mud bottom. Limetree Bay has extensive mud flats which 

 are covered in some areas with grass. The mangrove trees along the 

 shore have no oysters, but orabs are abundant among the roots. On 

 the flats there are numerous univalve mollusks and in the mud the clam 

 Chi one pubera is plentiful* Land orabs are present in abundance on shore* 



Discussion and Recommendations 



Oysters of Puerto Rico and the Virgin Islands 



Oysters of one type or another are almost world wide in their 

 distribution, being found along the coasts of nearly all the continents 

 and islands* Although certain chaise teri sties of the different oysters 

 are sufficiently marked to allow a separation of oysters into major 

 groups, there is considerable confusion as to the correct classification 

 of oysters in the smaller groupings, particularly in the genus Ostrea * 



Among the most important distinguishing characters of the members 

 of the genus Ostrea are the dentition of the inner shell margin, the 

 structure and shape of the beak, and the coloration and location of 

 the scar of attachment of the posterior adductor muscle. The latter 

 character has been shown to be of considerable importance by Nelson (1938) 

 for it is related to the presence or absence of a promyal chamber. Space 

 for the chamber results in a deeper valve with the muscle soar more distally 

 located. It is known that oysters having a promyal chamber are dioecious 

 and oviparous, while those without it are hermaphroditic and larvi parous* 

 Because of these differences, McLean (1941) has grouped the species of 

 Os trea into two subgenera, Ostrea and Crassostrea . His key to the species 

 of Ostrea of the Western Atlantic is the best available at the present 

 timel A~revision of the classification of oysters is being made by Ranson, 

 the French oyster specialist, but his work is not yet complete. 



Dall and Simpson (1900) classified the c(»imon oyster of Puerto 

 Rico as Os trea virginioa Gmelin* Mattox (1948) agreed with this 

 classification, but as a result of a more recent study (Mattox, 1949), 

 he considers it as Ostrea rhitophorae Guilding* The differences be- 

 tween the conraion oyster of Puerto Rico and the Virgin Islands and 

 the Eastern oyster (0. virginioa) of the United States strengthen the 

 case for 0. rhizophorae . It is small, not exceeding 2-3/4 inches in 

 length, oTten ribbed radially, and flourishes in lagoons, attached to 

 the vertical aerial roots of the red mangroves between low and high 



12 



