26 



Great Rock. Both young- and astyris were found in greater numbers on the southern portion of the 

 bed than on the northern. Along the eastern edge of the bed on the hard bottoms the red sponge 

 was found, and a smaller amount on the central part; very little was found where the bottom was 

 soft, and the number of young diminished whei'e the amount of sponge was excessive. The number 

 of oysters to the square yard, the mean of thirty-two observations made on different parts of the 

 bed, is 0.24, which is somewhat larger than on the Great Rock, probably on account of shoal er water 

 in which the dredging was done. The oysters scattered around the bed are similar to those on it, 

 though they grow somewhat larger and have cleaner shells. To the westward the young were 

 present in moderate numbei*s and with the usual proportion of astyris. But little spolige or grass 

 was found in this direction, but to the southward both increased, and young and astyris disap- 

 peared. The number to the square yard, on the area occupied by scattered oysters, the mean of 

 thirteen observations, was 0.06. 



Thoroughfare Beds. — On the eastern side of the Sound, opposite Little Fox Island and south of 

 the Great Rock, are two beds of moderate size, called the Little Thoroughfare and Great Thorough- 

 fare. The area of the former is 720,000 square yards, and the area of the latter, 1,597,000 square 

 yards. 



The depth of water over the Little Thoroughfare is from 15 to 31 feet, the deep water being- 

 found over the western and southwestern portion and shoaling from thence gradually to the north- 

 ward and eastward. Over the Great Thoroughfare the depth is from 1(5 to 54 feet, the deep water 

 being found on the western and northwestern edge of the bed and shoaling to the southward and 

 eastward. The space separating the beds is about one-fourth of a mile wide, and has over it a 

 depth of water from 20 to 40 feet. The beds are unbroken except about the edges, where the 

 oysters arc scattered. On the western side of the Great Thoroughfare, where the bed extends to 

 the soft muddy bottoms, the usual detachment of the oysters into groups is noticeable, but about 

 the other boundaries, where the bottom is hard sand, the oysters are distributed more thinly and 

 the breakage not distinguishable. The distribution of oysters was more even on the Great Thor- 

 oughfare than on the Little. Thoroughfare bed, the largest number on the latter bed being found 

 on the western part, while on the former the largest number was about the central portion. The 

 bottom on both beds is hard, consisting of a stratum of shells and oysters 1 or 2 feet thick, over a 

 stratum of sand. Very few observations of the character of the substratum were made, the depth 

 of water being too great to permit it, but as the bottom as far as the channel was hard, and large 

 numbers of shells and oysters were brought up from the western border, it is probable that the 

 shell stratum continues as far as the muddy bottoms. 



The oysters w r ere of moderate size, usually single, but occasionally in small clusters. Large 

 numbers of young were found on the extreme northern part of the Little Thoroughfare and on the 

 central and western portions of the Great Thoroughfare bed, while very few young were found on 

 the eastern part of the latter. Some of the young had been destroyed by dredges and a few by 

 drills, though not many of the latter (astyris) were discovered. A small amount of sponge and 

 grass was found about the edges of the beds. The number of oysters to the square yard, on the 

 Little Thoroughfare, the mean of nine observations, was 0.14. On the Great Thoroughfare, the 

 mean of ten observations was 0.11. On the area occupied by scattered oysters, the number to the 

 square yard, the mean of seven observations, was 0.05. 



The California Bed. — This bed lies on the eastern side of the channel, opposite the thorough- 

 fare into Pocomoke Sound, and south of the Great Thoroughfare bed. It extends in a north and 

 south direction about 3 miles, and is very irregular in shape. About the center it is divided by a 

 mud slough one-eighth of a mile wide. The area of the bed is 3,915,000 square yards. Along the 

 western part of the bed runs a narrow ridge, which is comparatively unbroken and appears to be 

 the original of the bed defined on the chart. To the eastward of this ridge the stratum of oysters 

 and shells is thinner, though the shells and oysters are spread quite evenly, diminishing in numbers 

 as the edge of the bed is approached. West of the ridge and also in the vicinity of the dividing- 

 mud slough, the bed is broken into detached groups of oysters and shells. The depth of water is 

 from 17 to •'!!) feet, the deepest water being found on the northwestern and western parts of the 

 bed. Except about the western border, the bottom is hard. Only a few observations of the char- 

 acter of the bottom could be made, either on the bed or in its vicinity, the depth of water being 



