YOL. XVII.] PHILOSOPHICAL TRANSACTIONS. 513 



cartilages, one at each end, whereas the oyster and scallop are with one only in 

 the middle. The natural posture they keep to, neither lying on the side, as 

 those I saw, nor set up in the sand like eggs in salt, with the sharp end down- 

 wards, and the opening side turned from the torrent, as the people say, I leave 

 to be further inquired into ; but I saw them lying in part opened, and putting 

 forth their white fins, like a tongue out of the mouth, which directs the eye to 

 them in the water, being otherwise black as the stones in the river. The backs 

 of the shells just about the hinges, on which the valves open, are all broken 

 and bruised, and show the several crusts and scales composing the shell, and is 

 probably caused by the many great stones that are driven over them by the 

 floods, which are most impetuous after any little rain. The insides of the 

 shells are of an oriental and pearly colour and substance, like a flat pearl, espe- 

 cially when first opened ; and I am informed, that in some shells, under the 

 first coat, lies a liquor very orient and clear, which moves on the pressure of 

 the finger, but that such a muscle never has a pearl. 



The part where the pearl lies is in the toe or lesser end, at the extremity of 

 the gut, and out of the body of the fish, between the two films or skins that 

 line the shell. I believe that this pearl answers to the stone in other animals, 

 and certainly like that increases by several crusts, growing over one another, 

 which appears by pinching the pearl in a vice, by which the upper coat will crack 

 and leap away. This stone is cast off by the muscle, and voided as it is able ; 

 and many shells that have had pearls in them are found now to have none, 

 which will appear by these instances. The shells that have the best pearls are 

 wrinkled, twisted, or bunched, and not smooth and equal as those that have 

 none. And the crafty fellows will guess so well by the shell, that though you 

 watch them ever so carefully, they will open such shells under the water, and 

 put the pearls in their mouths, or otherwise conceal them. 



An Account of two Plants lately brought from the Cape of Good Hope. Com- 

 municated by Dr. Sloane, R.S.S. N° I98, p. 664. 



1. The silver pine tree. — The twig of this tree* had a great many 

 leaves set round it, very close to one another, so as to hide the twig itself; 

 each of the largest of them being about 4 inches long, and 4 of an inch 

 broad in the middle where broadest ; from whence they decrease towards both 

 extremities, ending in a point, like those of the osier willow, only broader, 

 and all covered over with thickest, finest, and longest white silken hair or 

 down that ever any plant I remember to have seen. The cones are of 



* Prolea argentea. Lino. 

 VOL. III. 3 U 



