

6 



number of young' smaller than the marketable size, and oilier pertinent remarks, were noted after 

 each haul. At intervals during the day the number of dredging vessels in sight was recorded for 

 reference, and subsequently an attempt was made to collect data for the estimation of the number 

 of oysters taken in a day by each sail. At each anchorage the current was measured. 



From the results given by using the pole in the boats and the dredge in the schooner, the 

 outlines of the beds have been traced on the chart, the lines defining their limits including nearh 

 all stations when the number of oysters was greater than one-tenth to the square yard, and though 

 in some portions of the beds, as shown on the charts, the number was less than one-tenth, yet 

 other circumstances, such as the character of the bottom, the amount of shell brought up by the 

 dredge, &c, have caused them to be included as pari of the beds. 



The limit of scattered oysters can only be considered as approximate, as the lines were drawn 

 from information received from local oystermen and from such observations as we were enabled to 

 make ourselves. As has been already stated, the boats were unable to ascertain the positions of 

 any but the solid beds or large clusters, and the schooner not being able to work iu less than 8 

 feet of water, our ability to determine the area covered by the scattered oysters was necessarily 

 limited. As that, area, and indeed that of the solid beds also, is variable, changing from year to 

 year, the line inclosing the scattered oysters may be considered as accurate as it is necessary to 

 have it. 



TIDES. 



The mean rise and fall of the tides in the sounds is so slight (amounting to 2.3 feet in Tangier 

 and 2.4 feet iu Pocomoke). and generally the depth of water over the beds so great, that it was not 

 considered necessary to establish tide gauges except in one case; such tidal corrections as liave 

 been applied to the soundings have been obtained from the Coast Survey Tide Tables. A com. 

 parison of the rise and fall of the tides, as given by those tables, with that given by a tide staff 

 erected at Clay Island Light-House, showed that during the months of October and November the 

 greatesl difference was nine-tenths of a foot. Owing to the vernal and autumnal gales the most 

 considerable departure from the usual height of the tidal water occurs at those seasons, and it is 

 therefore probable that one toot will represent the maximum error of the Coast Survey Tide Tables, 

 and 3i feet the maximum rise of the tide in either sound. Considering the great depth of water 

 over the majority of the beds, it was concluded that the slight variation in those depths caused by 

 the tides could have but little influence on the oysters, and consequently the correction of sound 

 ings except in depths less than three fathoms has been neglected. 



r 



SPECIMENS. 



The oyster specimens. Tot in number, were selected from large quantities brought up by the 

 diedge and tongs, the endeavor being to take three specimens of different ages from each locality. 

 < >ne specimen of an adult oyster of two years' growth or more, one of from one to two years' growth, 

 and one less than a year old, were usually selected. Shells, either old or new, and especially those 1 

 having a large number of young clinging to them, were also occasionally preserved, and though a 

 few specimens of oysters that had been transplanted were secured in order to show the effect of 

 change of water, bottom, and depth, yet no examination of the planted beds was undertaken. In 

 the selection of specimens we attempted to reserve such as would indicate the effect of different 

 natural conditions. At the close of the day's work the oyster specimens were washed in salt 

 water, opened carefully with a sharp pointed, thiu bladed knife, and the upper valve detached from 

 the muscle, and then replaced. A small wooden peg was then placed between the bills of the 

 shell, the valves tied tightly together with twine, and the oyster wrapped iu cotton cloth of a very 

 open texture. The whole was placed in alcohol. The wooden peg kept the shell open sufficiently 

 to allow the alcohol access to the body of the animal, and the cloth wrapper prevented the destruc- 

 tion or loss of anything of interest which might be attached to the shell. Six parts of alcohol to 

 four of water were used, aud to each specimen was attached a wooden label showing from whence 

 the oyster came. 



