58 



those of the Labrinthodont reptiles, in others the throat is 

 protected by gular plates, a fashion retained in the Carboniferous 

 amphibia. Again, in some species the scales are surface pitted, 

 like the scutes of Crocodiles. While, in the notochordal weak- 

 limbed amjihibians of the coal measures, ^yiih minute body scales, 

 and partly osseous skulls, we cannot fail to recognise structural 

 peculiarities now found in the swamp-dwelling mud fishes. Thus 

 in the anomalous " scaled sirens," we have the "persistent tyjie" 

 of an ancient group of fishes, in which now, as in the old time, 

 the piscine and amphibian characters are so xuiited as to completely 

 efi"ace the line of demarcation between the orders, and effectually 

 link the fishes to the reptiles. 



A cordial vote of thanks was awarded to Miss Crane for her 

 valuable paper. The vote was acknowledged by Mr. Crane ; and 

 then an examination of the specimens produced in illustration of 

 the paper, and a conversation respecting the subject of it, was 

 entered upon, the President, Mr. G. D. Sawyer, Mr. Crane, 

 Mr. Wonfor, and Mr. Haselwood, taking part, and the latter 

 suggesting the giving of a few elementary lessons in such sciences 

 as that of which it treated, in order to better prepare some of 

 them to appi-eciate them when discoursed upon. 



February 22xd. 

 MICROSCOPICAL MEETING.— Mr. T. W. WONFOR ON 

 ARTIFICIAL DIATOMS. 

 It is weU knoAvn to chemists that if fluor spar and sulphuric 

 acid be mixed together in a platinum or leaden vessel, so as to 

 form a paste, and gentle heat be applied, that fmnes of hydrofluoric 

 acid, which has a great afiinity for silica, are given off. Advantage 

 is taken of this property in the arts to produce etcliings on glass. 

 The operation consists in evenly smearing the surface of tlie 

 article to be operated on with a coating of wax or a resin,ous 

 compound known as etching ground. On this prepared surface 

 the design is traced in the ordinary way with a pointed instrvunent. 

 The glass is then placed, waxed siu'face downwards, in a sliallow 



