114 Mr. J. Gk)uld on a new species 0/ Platycercus. 



at present to enter into details ; all that I now wisli to commu- 

 nicate is the result at which I have arrived ; and in a short time 

 I hope to have the pleasure of publishing, at length, my observa- 

 tions in connexion with this interesting subject. 



The excavating instrument of Pholas and Teredo is formed of 

 the anterior portion of the animal, in the surface of which are im- 

 bedded siliceous particles. The particles penetrating the skin 

 give to it much the character of rasping-paper. The whole forms 

 a rubbing surface, which being applied closely to the bottom of 

 the cavity by the adhesion of the foot, enables the animal to rub 

 down, and so penetrate, shale, chalk, wood, or even the hardest 

 limestones and marble. 



Saxicava rugosa is also furnished with a rasping surface co- 

 vered with siliceous particles. This surface, however, in this spe- 

 cies is formed entirely of the anterior portion of the mantle, the 

 margins of which being united are much thickened, forming a 

 sort of cushion capable of considerable protrusion at the will of 

 the animal. The foot is small, and passing through a much-con- 

 stricted orifice, gives origin to a byssus, which anchors the shell 

 close to the base of the excavation, and thus holds the rubbing 

 apparatus in immediate contact with the part to be excavated. 



XVII. — On a new species 0/ Platycercus. By John Gould, 

 F.R.S. &c. 



Dear Sir, 20 Broad Street, Golden Square, Jan. II, 1845. 



My collector, Mr. Gilbert, has lately sent me the description of 

 a new Platycercus discovered on the Darling Downs at the back 

 of Moreton Bay, on the east coast of Australia, and which he 

 states far surpasses in beauty every other species of the genus yet 

 discovered. I have therefore thought it of sufficient importance 

 to the ornithologist to send you a copy for insertion in the ' An- 

 nals of Natural History.^ 



Band across the forehead half an inch in breadth, scarlet, 

 fading around the eyes, lores and cheeks into pale lemon-yellow, 

 which again gradually blends with the green of the under surface ; 

 crown of the head and nape blackish brown ; sides of the neck to 

 the shoulders verdigris-green with yellowish reflexions ; back 

 grayish brown ; rump and upper tail-coverts verditer-blue, the 

 longer coverts with a band of black at their extreme tip ; prima- 

 ries and secondaries black edged with bluish green ; shoulders 

 with a spot of rich vermilion ; under wing-coverts and edges of 

 the pinions verditer-blue ; two middle tail-feathers olive-brown at 

 the base, gradually passing into greenish blue at the tip with olive 

 reflexions ; the three outer feathers on each side with a narrow zig- 



