262 Transaction, — Zoology. 



of mammalian and other skulls, the sternum and sternal ribs of reptiles and 

 mammals, and other partly or wholly cartilaginous portions of the skeleton 

 of the higher animals. 



The skeleton of Ceratodus was prepared from a specimen which had been 

 for a long time in alcohol ; when cleaned it was put through the process 

 described above, as a whole, the cartiliginous and bony portions being too 

 intimately united to allow of the former being prepared alone. This skele- 

 ton has now been prepared for upwards of six months, and shows no signs 

 of deterioration. During the whole process it only lost -^^g of its length, 

 and even the notochord is hardly more shrunk than in a spirit specimen. 



The trouts' skulls were prepared by plunging in boiHng water for a few 

 seconds, and then removing the membrane bones ; the chondrocranium, 

 Meckel's cartilages and the branchial arches only being put through the 

 glycerine jelly process. After nearly six months the shrinking of the chon- 

 drocranium is so slight that the membrane bones fit into their places with 

 almost perfect accuracy. The chief drawback to this preparation is the bad 

 colour taken by the cartilage bones, which of course have to be put through 

 the preserving process ; they assume much the colour of the cartilage and 

 cannot be brought to the same state of whiteness as the membrane bones, 

 which are dried at once. 



The same objection applies to such parts of the foetal skeletons, which 

 were put through the preserving process entire. In the case of long bones, 

 the plan was adopted of macerating until the epiphyses could be easily 

 removed, and then preparing these latter alone, and afterwards wiring them 

 on to the shafts. After several weeks the shrinking in these is quite 

 unnoticeable. 



3. Internal organs. The method has been tried for the hearts of the 

 skate, dogfish, and leopard-seal, the stomach and intestine of the skate, 

 and brains of the skate and sheep. All such structures are first thoroughly 

 hardened in alcohol or chromic acid, and are then subjected to the same 

 process as the cartilaginous skeletons, care being taken to support them 

 carefully in the desired position while drying : veins, for instance, have 

 to be kept open with cylinders of card-board, and so on. It is best to 

 make any dissection of these organs after their removal from alcohol, they 

 can, however, be trimmed conveniently when thoroughly dry. As a rule 

 the thinner organs are more successful than those of considerable thick- 

 ness ; the intestine of the skate, for instance, with the spiral valve displayed, 

 shows no perceptible shrinking: while the ventricles of the seal's heart 

 are perceptibly thinner than before drying ; none of the details of structure, 

 however, being lost. These organs, like the bones, assume a dark colour, 

 and are not very attractive as preparations: they are, however, greatly 



