Parker. — On preserving Cartilaginous Skeletons. 259 



about to be described enough to make me feel tolerably confident in recom- 

 mending it as of special value in the case of cartilaginous skeletons, and 

 useful for hollow viscera, the exoskeletons of Crustacea and Echinoder- 

 mata, etc. 



It will be advisable to describe separately the chief applications of the 

 method. 



1. Cartilaginous skeletons, I find the best way to clean the skeletons of 

 fresh Elasmobranehs is to clear away the flesh, etc., very roughly, after 

 removal of the skin and viscera, then to dissect away the gill-arches, and 

 then to plunge the body into boiling water for a few seconds. This softens 

 the muscle and connective tissues so much that their removal is rendered 

 quite easy, while, if prepared in the cold, it is almost impossible to remove 

 the tough perichondrium without injury to the cartilage. In the case of even 

 moderate sized specimens it is often necessary after separating the skull, 

 vertebral column, and fins, to dip each part again into boiling water. With 

 very large specimens it is necessary to separate the different regions of the 

 skeleton, and even to cut the vertebral column into segments before plunging 

 them in the water, as otherwise no ordinary vessel will sufiice for their 

 immersion. In the case of spirit specimens parboiling is not necessary. 

 The gill-arches should be thoroughly hardened in spirits and then cleaned 

 by ordinary dissection ; even a slight application of heat causes the 

 separation of their delicate cartilages. In the same way no heat must be 

 employed in the preparation of persistent notochords, as for instance in the 

 case of CallorhyncJms. 



When thoroughly cleaned, fresh specimens should be placed in strong 

 methylated spirit for two or three weeks. This hardens the cartilage and 

 produces a certain amount of shrinking. In the case of large skeletons 

 (sharks, etc.), this operation may be dispensed with on economical grounds, 

 but without it the results are never so satisfactory. 



When thoroughly hardened the specimen is transferred to one of the 

 following fluids : — 



Glycerine Fluid, A. 



Glycerine 1 litre. 



Water 1 „ 



Corrosive sublimate . . 10 grains. 

 Alum 10 „ 



Glycerine Fluid, B. 



Glycerine 1 litre. 



Water . . . . . . 1 „ 



Concentrated solution of 



Phenol 5 c.c. 



Alum . . . . . . 10 grams. 



Of the two fluids, B seems to give the best results, the colour of its 

 specimens being better than that of those prepared by A. The alum may 

 be omitted if the specimen has been previously hardened in alcohol. It is 

 always advisable to use earthenware vessels ; indeed, this is necessary in 

 the case of A, as corrosive sublimate acts upon metals. It is also a good 



