In the giant scallop the distribution of the gential organs is 

 the same in both sexes. The organs occupy nearly the whole 

 of that portion of the body that lies beneath the foot that is not 

 occupied by the alimentary canal, and extend up dorsal to the 

 foot so as to form a thin layer over the surface of a portion of 

 the liver. When the organs are gorged with their products the 

 portions of the body that contain them are plump and compara- 

 tively large. When spawning has been completed they are 

 shriveled and small. In the adult there is no apparent separa- 

 tion into a pair of organs farther than by the possession of a 

 pair of ducts. These are not very conspicuous and enter the 

 kidneys of the respective sides near their dorsal ends. From 

 this point out, the sexual products traverse the lumen of the 

 kidney, so they are finally expelled into the water through the 

 external opening of the kidney. 



The products are expelled from the openings of the kidneys 

 in streams. The animal occasionally flaps its valves together dur- 

 ing the process so the products are thrown out of the shell and 

 dispersed in the water. For the most part the animal lies with 

 the valves separated and is rather indiflferent to outside stimula- 

 tions. At such times it is sometimes possible to pick a specimen 

 up out of the water without causing it to close its shell. Soon 

 after removal from the water, however, the animal recovers and 

 responds as usual. Replaced in the water it may or may not 

 immediately begin to spawn again. 



The relation of the genital ducts and kidneys of lamellibranchs 

 has long been considered as important for its possible bearing 

 on the relation of the kidneys to nephridia and the pericardium 

 to a coelom. In the adult of this form the sexual ducts open 

 into the kidneys near their pericardial ends. Nothing is known 

 about their developmental relation. The openings are much 

 farther from the external openings of the kidneys than I have 

 found to be the case in Yoldia lamatula (5) or Nucula delphino- 

 donta (7) but not so far as in the case of Solenoma where, as 

 Stempell has found (30) for one species (Solemya togata) and 

 I have verified for another one (Solenomya velum) the ducts 

 open very near the pericardial ends of the kidneys. In view of 

 what we know about these and other species studied and 

 reported by Pelseneer, (22) Stempell (29) and others, where it 



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