892 TWO NEW SPECIES OP MACROPUS, 



Tail slender, on the under side nearly bare, on the upper covered 

 with short dark hair. No white tips to the tail. 



I have already mentioned, that I had the opportunity of examin- 

 ing the skull of M. Jukesii, but unfortunately, the skin before it 

 arrived in Sydney had been preserved in common salt, which mode 

 of preservation had the result, that the bones and teeth of the 

 specimen were covered with a thick layer of some white stuff, which, 

 though not interfering with the general shape of the skull, rendered 

 the examination of the sutures as well as other minor osteological 

 details of the same very difficult. Wishing to get rid of this white 

 interfering cover, I tried to dissolve it in boiling water but not 

 having succeeded, I went to Dr. A. Leibius to find out about its 

 chemical nature. It proved to be magnesia (*), which could only 

 be dissolved by boiling the skull in a solution of muriatic acid. 



Fearing however, that even a very weak solution of acid would 

 destroy the thinner bones, I preferred to abstain from the experi- 

 ment and to remove as much as possible the white crust mechanically 

 by scratching it off with a scalpel. I succeeded only partly, some of 

 the suture remained still not distinct and the molars could not be 

 made free from the incrustation of magnesia, without destroying 

 them. 



The skull is elongated ; examined from above (Fig. 2) shows two 

 very marked ridges running from the orbital margin of the frontal 

 bone, along the parietalia, to the exteimal corners of the imparietal 

 bones. 



Examined from the side, (Fig. 1) the skull appears not of great 

 height in the region of the fronto-parietal suture and shows a very 

 marked bending of the premaxillary region downwards. The apex 

 of the angular process of the inferior margin of the zygoma is 

 opposite the posterior cusp of the second molar. The palate 



* Dr. A. Leibius who kindly examined the above-mentioned white sub- 

 stance, expressed the opinion that the magnesia crust on the skull was 

 probably the result of decomposition of magnesium cloride, which is nearly 

 always contained in the unpurified common salt, which had been used 

 in this case for preserving the skin. The other product of this decom- 

 position — chlorhydric acid — had the effect of softening the bones. I think 

 this case shows sufficiently the unfitness of using uupurified ordinary salt 

 for preserving Zoological specimens. 



