The Three-angled Clams 



The activity of the animal is vouched for by Stutchbury, 

 who, having dredged one in Sydney harbour, laid it on the gun- 

 wale of his boat, whence it leaped over a four-inch ledge and 

 returned to its submarine abode. Strange migrations of these 

 shell fish occur. All at once a region which has yielded abun- 

 dantly will become absolutely barren oi them. 



The Pearly Trigonia (7. margaritacea, Lam.) is obliquely 

 rounded in outline, and moderately convex, with ribs and nodules 

 not very pronounced. It is the largest of living trigonias, and 

 remarkable for its rosy purple pearl lining. Length, 2 inches. 



Habitat. — Tasmania. 



380 



