70 



riot think it possible that the spat, if they are at any time contained within the gills or mantle, 

 could have escaped my notice. 



The observations as to the sex of the oyster were continued late in the season, and though the 

 ova and spermatozoa in a number of oysters were in apparently good condition as late as the 1st of 

 October, yet those products of generation appeared in best condition in the largest number of 

 animals during July, and a considerable disintegration of the eggs was noticed by the end of that 

 month. As far as I could ascertain, the condition of both ova and spermatozoa depended upon the 

 depth of water, though the rule was not invariable. The generative products of the deep-water 

 oysters reached a state most favorable for reproduction several weeks after the same had occurred in 

 the shoal water; and, in general terms, neither ova nor spermatozoa in most of the oysters, in either 

 deep or shoal water, after the middle of August, was in a state favorable for fertilization. Large 

 numbers of oysters in all depths passed through the spawning season without expelling the con- 

 tents of the generative organs. I found this the case especially on the beds on the western side 

 of Tangier Sound, above Kedge's Strait, where, on the Sth and 9th of October, we found many 

 oysters fattening with the generative matter unexpelled. I was informed that this was not unu- 

 sual, and that it injured the oyster for marketable purposes. As late as the Sth I found oysters 

 with the generative matter in good condition, and on the 7th of October I succeeded in securing 

 from oysters taken from Kedge's Strait a sufficient amount of ova and spermatozoa to make experi- 

 ments in artificial impregnation, and was successful in producing one embryo oyster. Probably 

 had I used greater care a larger number would have resulted. 



During the season of 1878 we observed large numbers of astyris in the shells of the mature 

 oysters and attached to those of the young. In mauy cases they were found in the holes which 

 had been bored in the shells of the latter. As we could not find any known enemy of the oyster 

 in sufficient numbers to account for the evident damage done, and as so many circumstances 

 pointed to astyris as the cause, I concluded that the boring must be doue by that animal, and 

 alluded to it in my previous report. The specimens preserved were described by Mr. W. H. Dall, 

 and the description appended to that report. During the past summer we have fouud a much 

 larger number of the rough welks (iirosalpinx cinereus) than during the previous season, and 

 though they were not fouud in as large numbers as the astyris, yet their presence inclined me to 

 question the conclusions arrived at during the season of 1878. I accordingly collected a large 

 number of astyris and placed them in an aquarium jar with a number of young oysters, changing 

 the water constantly and inspecting the animals frequently. The observations were continued for 

 over a week, and at the end of that time both oysters and astyris were alive, but there was no 

 evidence of any boring, nor did any inspection show an inclination in that direction upon the part 

 of the astyris; on the contrary, they soon left the shells and went to the bottom of the jar. I 

 then collected a number of urosalpinx cinereus and subjected them to the same test. At the end 

 of four days one oyster had been bored and one welk was found at work on the shell of another. 

 The rough welk is known to do great injury to the oyster in Long Island Sound, and the destruc- 

 tion of the young, alluded to in my previous report as due to the drills, may be effected by this 

 animal. That large numbers are destroyed by the welks cannot be doubted; but as it is possible 

 that the astyris may also assist in this destruction, a more extended investigation of this question 

 than I was enabled to make is desirable. 



An analysis of several specimens of the water of the Sound and bay, by Prof. 0. E. Monroe, 

 of the Naval Academy, is appended to this report for use in comparing the localities investigated 

 with others whose investigation may be subsequently attempted. The specimens have been selected 

 from those taken on different stages of the tide and from different sections. 



The only noticeable change on the beds this season was that the amount of red sponge appeared 

 to be much less than in 1878. In other respects they are, to outward appearances, in a similar state, 

 though the dredgers report them as much broken up and with an increased amount of debris. 



INFORMATION OBTAINED FROM "RECORD OF STATISTICS." 



The member of the party on duty at Crisfleld inspected, during the season, 490 vessels directly 

 engaged in the oyster fishery, and the results of these inspections have been recorded in the record 

 of statistics, which record, to a great exteut, explains itself. 



