Anatomy of the Food Mollusks 



33 



In the giant or northern scallop, cilia unite some of 

 the filaments near the free margin of the gill, but near its 



Fig. 6. — A portion of the gill of the scallop (Pecten irradians) 

 showing the folding of lamellae. The reference-letter / 

 designates one of the filaments. The letters c s indicate 

 ciliated spurs that are sectioned, and i u an interlamellar 

 union. 



base they are joined by bands of fine tissue, thus form- 

 ing a much more stable union. This growing together 

 of adjacent filaments becomes very much more extensive 

 in the clams and the oysters. 



Comparing the gill of the little neck clam, Venus, with 

 that of the scallop, we find the same folding of the 

 lamellae, and largely developed interlamellar partitions. 

 But the filaments are small and all of the same size. The 

 greatest difference in the two cases is that in Venus 

 the filaments have grown together very extensively on 

 their inner margins, leaving mere slits here and there 

 where water may enter the gill. A very curious struc- 

 ture is found in this gill. Thin walled sacs grow from 

 the interlamellar partitions and the filaments into the 



