22 OYSTER BOTTOMS IN MATAGORDA BAT. 



of the red egg cases of the so-called borer, Purpura. These cases are 

 often referred to by the oystermen as " red grass." The drumfish is 

 said to be destructive at times. 



One of the chief characteristics of the oyster growth is the scarcity 

 of young oysters. This is a serious matter, and indicates an ap- 

 proaching period of unproductiveness unless there is a speedy change 

 for the better. 



MAD ISLAND REEF. 



This is the smallest of the Matagorda Bay " long reefs." It 

 stretches in a generally southeasterly direction for a distance of about 

 2,000 yards from the north shore at Mad Island West signal, with 

 an average width of about 300 yards and an area of about 93 acres 

 exclusive of the exposed crest, which extends for practically its 

 entire length. Apparently this reef has not grown at its offshore 

 end as have Half Moon and Shell Island reefs, a fact that may be 

 explicable on the assumption, based on local reports, of its periodical 

 destruction. It is known that on at least one occasion, about 1896 or 

 1897, it was almost if not entirely destroyed by fresh water, grass, 

 sand, and debris carried upon it by a freshet in the drainage basin of 

 Mad Island Lake, and it is stated that similar disasters had before 

 visited it. After an interval of several years it became reseeded by a 

 heavy set of spat, and during the season of 1904—5 the oysters became 

 marketable and were in considerable demand at Matagorda. The reef 

 lies on a deep, dense bed of shells, compacted with fragments and 

 sand, lying on a foot or two of soft mud, which in turn is underlaid 

 by hard mud. The margin of the bed lies in a depth of about 1J 

 feet of water at the shore, with gradually increasing depth to 5 feet 

 offshore. The crest, which is close to the eastern margin, is more or 

 less covered with a growth of raccoon oysters, and at its inner end 

 has an elevation of 6 or 8 inches above the low-water plane adopted 

 in this report. The eastern margin is well defined and continuous, 

 and it is near this limit only, over an area of about 23 acres, that mar- 

 ketable oysters are found. There was in April, 1905, on the reef east 

 of the crest, an average per square yard of about 42 adult oysters and 

 28 small ones, and from these data it is estimated that there were at 

 that time approximately 9,000 barrels of marketable oysters. Both 

 young and adults had well-shaped, clean, thin shells and the market- 

 able stock was of good size and flavor, with a considerable proportion 

 of single oysters and few clusters of more than 3 or 4 individuals. 

 The preponderance of single oysters and small clusters is directly 

 attributable to tonging, a number of boats having operated on this 

 part of the reef during the season preceding. 



On that part of the reef lying west of the crest the conditions are 

 quite different. The area is much larger, about 70 acres, and the 

 reef slopes gradually away from the crest to a more or less indented 



