BARKER ON THE FRESH- WATER PEARL MUSSEL. 113 



itself, then passing under or rather on one side of the stomach, and thence 

 through the pericardium and heart, terminates behind and below the 

 inferior adductor muscle. In this course it is of nearly uniform dia- 

 meter, about the size of a crow quill, and is capable of considerable 

 distention. As far as I can judge, there are free communications be- 

 tween the alimentary canal and the water-vascular system, so as to 

 admit of the foot being contracted suddenly, and the water expelled by 

 mouth or water pore, or both. 



I think the specimens on the table, which are intended for the 

 Museum of the Eoyal College of Surgeons, exhibit these structures dis- 

 tinctly ; with regard to the nervous system, it is also shown in one of 

 the preparations, which exhibits the well-known distribution of the 

 nerves in the Lamellibranchiate Mollusca. I may remark that distinct 

 branchial ganglia are found on the nerves supplying the gills : I have 

 failed hitherto in demonstrating, however, the auditory capsules in the 

 "Ohio. 



Mr. J. B. Doyle observed that he had found the Pearl Mussel in 

 several parts of Ireland. Some years since, when travelling in Donegal, 

 he procured some fine specimens of pearls from the rivers in the vicinity 

 of Letterkenny. At that time there was a revenue officer at Eamelton, 

 who realized more by the sale of pearls than by his situation. The ha- 

 bitat of the Pearl Mussel he had found almost invariably to be in deep 

 pools of rivers which flow through alluvial or marshy bottom lands. It 

 is often extremely difficult to see the Mussels, in consequence of the shells 

 being of the same colour as the mud in which they are imbedded. The 

 favourite season for taking them is during the summer months, when 

 the rivers are low. Selecting a calm bright day, the fisherman sallies 

 forth, armed with a sparp-pointed wattle and a large wooden scoop. 

 Having stationed himself upon the brink of the pool, he waits until he 

 sees some of the Mussels move, but which they do with great rapidity 

 by the aid of their strong muscular foot. Sometimes they lie basking, 

 as it were, in the sunshine, the foot extended, and mantle visible. They 

 thus form a conspicuous object at the bottom of the pool, and a convenient 

 mark for the fisherman, who instantly thrusts his pointed stick between 

 the valves, and thus lifts the shell cautiously out of the water, repeating 

 the process as long as he finds an open shell. Having thus discovered 

 the situation of the bed, he wades into the pool and shovels them out 

 by wholesale on the bank. The heap is then carefully examined, and 

 all the deformed and wrinkled shells are selected, as likely to contain the 

 best pearls. The residue, or healthy Mussels, are also carefully examined, 

 although, generally speaking, with little success. Some years ago he 

 (Mr. Doyle) saw an extensive pearl fishery at Portglenone, on the Bann. 

 At this place it was customary to throw the Mussels into a large heap to 

 decompose, which they do very rapidly. They were then taken and 

 washed in large tubs, the mass of shells and pulp being stirred with a 

 stick. After repeated washings the shells and grosser parts were removed, 

 and the pearls sought for at the bottom. 



