27 



too great. Such as were obtained showed a substratum of hard sand, and it is probable that the 

 substratum is similar on all parts of the bed. 



On the central portion of the bed the oysters were single, of moderate size, and fair quality, 

 but not numerous. Very few young, very few astyris, and but little red or gray sponge were dis- 

 covered. On the western part of the bed the oysters, though similar in character, were in greater 

 numbers, young and old, and where the number of young increased, a proportional increase in the 

 number of astyris was noticed. On the eastern part of the bed the number of oysters, young and 

 astyris, considerably diminished. About the edges of the bed the grass, sponge, and- sea-weed 

 increased, and where this occurred a decrease in the number of young was noticed. The number 

 of oysters to the square yard, the mean of thirty-six observations, was 0.21. On the area occupied 

 by scattered oysters, the number to the square yard, the mean of eighteen observations, was 0.06. 

 On account of the depth of water, and other unfavorable circumstances, both results must be 

 regarded as a much rougher approximation to the real number than in the cases of the beds pre- 

 viously described. 



Johnson's Bed.— This bed lies on the eastern side of the Sound, immediately to the westward 

 of the 3-fathom shoal off Watt's Island Light-House. The bed is separated into two portions, of 

 nearly equal area, by a dividing space of sand which extends north and south, following the 

 general direction of the bed. Each portion is about one-eighth of a mile, and the northern and 

 southern extremes are separated one mile and a quarter. The area of the bed is 1,395,000 square 

 yards. The bed is unbroken, except about the edges, and the oysters exist on the entire area, 

 though unevenly distributed, the larger number being found about the center of the bed. The 

 bottom is comparatively regular, the depth of water being from 24 to 36 feet, the greater depths 

 being on the western part and the least on the eastern part of the bed. On account of the depth 

 of water and unfavorable nature of the weather during the examination of this bed no observa- 

 tions of the character of the bottom were made. The lead showed a hard surface stratum, except 

 about the western edge, where mud was found. The oysters were large and single with many 

 young and drills (astyris). Very little sponge was found on the bed, but on the shoal to the west- 

 ward and between Johnson's and the California Beds there was a large amount of it. Very few 

 oysters were found in this area. The number of oysters to the square yard, the mean of four 

 observations, was 0.19. 



East of Johnson's Bed is a small rock, called a Parker's Hill," which for want of time was 

 neither surveyed nor examined. It is of little importance and seldom worked. 



Oak Hammock Bocks. — These beds are situated on the western side of the Sound at the entrance 

 to and in a large mud slough, which extends as far as Queen's Reach into the sand shoal surround- 

 ing Tangier Island. Each of the beds has a distinguishing name and is separated by mud 

 sloughs from the others, but as the areas are small and the outlines of the rocks very indefinite I 

 have included all of them under the name by which the assemblage is generally designated. The 

 beds extend northwest and southeast about three-fourths of a mile, and the area is irregular in 

 shape. The depth of water is from 9 to 24 feet, and the bottom is a stratum of shell, mud, and 

 sand, over a stratum of mud. Underneath this mud, where it was not too thick for penetration, 

 we found a hard stratum. The majority of the oysters were old, of small size, single, and in small 

 clusters. Neither young nor drills (astyris) were found, and but a moderate amount of sponge. 

 To the northward and westward of the beds the oysters are scattered in the mud in groups and 

 patches. The total area of the bed is 600,000 square yards. 



On the sand shoal between the Oak Hammock beds and the Woman's Marsh no oysters have 

 ever been found. 



DEKSITIES. 



Specimens of the bottom water taken on each bed, at all stages of the tide, have been tested 

 with the hydrometer and its readings reduced to a standard temperature of 60° Fahr. These 

 results show a maximum density of the waters of Tangier Sound of 1.0164, which was found in 

 the lower part, about the California Bock, at half flood-tide. The minimum density of 1.0111 was 



