ParKer.—On preserving Cartilaginous Skeletons. 261 
therefore not a great success; Raja was prepared without previous immer- 
sion in alcohol, and although a vast improvement on the ordinary skeletons 
of the same fish, is not so good as one could wish; but Cestracion and Trygon 
show, up to the present time, remarkably little alteration, the latter having 
been removed from eeees jelly for about six weeks, the former for fully 
three months. 
The success of the method is most marked in purely cartilaginous 
parts, such as the branchial arches, with their delicate branchial rays, 
which after many months retain their flexibility and translucence unim- 
paired. The thicker parts of the skeleton show, naturally, the greatest 
amount of distortion, and this is particularly marked when there is a 
thickish superficial layer of calcific matter, as in the jaws, etc., of Elasmo- 
branchs: with these parts, the shrinking of the cartilage always produces a 
slight cracking of the bony matter, but as a similar though less marked 
cracking is seen in spirit specimens, I do not see how it is to be altogether 
obviated, unless, perhaps, by using a larger proportion of glycerine. 
It is always advisable to allow the specimens several weeks to dry; when 
the surface no longer feels sticky they are varnished with a solution of 
white shellac in rectified spirit, the operation being conducted in a warm 
dry room, as the slightest damp produces precipitation of the shellac. If 
properly managed, two or three applications of this varnish produce a dry 
and smooth but not too glossy surface. * 
In mounting skeletons prepared in this way, the best plan is to make a 
framework of japanned wire, of such aform vaste serve as a series of rests, or 
“‘eradles,” for the several parts; the gill k ted on a llight 
wire framework. Unless sboulntely 3 necessary, no attempt should be made 
to fasten parts together with wire as in ordinary articulating, and when this 
has to be done, neither iron, copper, nor brass wire is admissible; silver or 
platinum only should be used if “ glycerine jelly A” has been employed, 
removed for examination ; this of course adds greatly to the value of the 
skeleton for teaching purposes. 
2. Partly ossified skeletons. Of these I have had prepared skeletons of 
Ceratodus, and of foetal calf and foal, and two skulls of the trout, and hope 
before long to get examples of the various genera of Ganoids and Urodela ; 
the method has also been aan with good results for the mesethmoid 
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