90 INLAND FISHERIES. 



extent, carrying the byssus organ outside the shell. The byssus 

 itself appears to be made of a single delicate transparent thread 

 (b) sometimes bearing a number of side branches, the end of each 

 branch forming a point of attachment. I have not had the time 

 at my disposal to determine the manner in which attachment is 

 actually accomplished, but it does not seem probable that it is 

 effected exactly as in 3fyt'ilus (mussel) and the young Pecten (scol- 

 lop), in which forms a groove on the ventral side of the foot leads 

 from the opening of the byssus organ out nearly to the tip. This 

 groove is converted into a closed tube, and the fluid secretion of 

 the gland is poured out into it. At the tip of the foot it is allowed 

 to come in contact with the body to which attachment is to be 

 made, and adheres tightly. The groove of the foot is now slowly 

 opened, and the secretion, upon coming in contact with the water, 

 is converted into a tough fibre. Myt'duH forms a niimber of threads 

 in this way, which extend out in various directions, and all unite 

 near the opening of the byssus gland. 



In the clam, an attachment having been made at a few points, 

 the thread may be greatly elongated by pouring the secretion out 

 directly into the water where it at once hardens, much as the 

 secretion from the spinning gland of a spider hardens, after its 

 extension, by coming in contact with the air. By fastening a 

 byssus thread from a clam 6 millimeters (nearly \ of an inch) in 

 length to the point of a needle, I have been able, by exerting a 

 gentle pull on the thread, to draw it out to a length of 5 centi- 

 meters (about 2 inches) in the space of about fifteen minutes. The 

 secretion was poured out at intervals, but not at any time with 

 much rapidity. The thread thus obtained appeared to be single, 

 was very elastic, and was possessed of some degree of toughness. 



POINTS BEARING ON THE DEVELOPMENT OF METHODS OF 

 CLAM CULTURE. 



The falling ofl' in the supply of clams in Rhode Island has for 

 some time been regarded with serious concern, and it is still 



