520 DESCRIPTION OF THE MUSEUM. 



cumference, and weighs upwards of six hundred 

 pounds. Peron mentions having seen at Timor, 

 specimens of this shell which two men could 

 with difficulty move. There is but one species 

 of the hippopus in the collection. 



2d. The mylilacece comprising the genera pinna, 

 modiola and mytilus. The animals of this family, 

 as also those of the next, attach themselves to 

 marine substances by means of filaments called 

 byssus, which being very delicate and silky in 

 two species inhabiting the Mediterranean, are 

 wrought into gloves and other articles, and 

 when mixed with wool and woven into cloth 

 they give it a sort of golden lustre. The pinna 

 squamosa is sometimes found three feet long. 

 Amongst the modiolce, of which we have six spe- 

 cies, we shall notice the m. tulipa, whfch is of a 

 pearly white, tinged with red, and the m. litho- 

 phaga, which penetrates into calcareous rocks. 

 There are twenty-seven species of mytilus in the 

 collection: that from Japan, that from the straights 

 of Magellan, and the opal muscle, are much va- 

 lued on account of their rarity and the beauty of 

 their colour. 



3d. The family of the malleacece, comprehend- 

 ing the genera crenatula, perna, malleus, avicula 

 and meleagrina. W^e have four species of cr.ena- 

 tula, found in the seas of New Holland ; and ten 



