1895- MORPHOLOGY AT THE NATIONAL MUSEUM. 261 



be parallel to the glass. It is a distinct advantage, under all circum- 

 stances, to have the front and back of a case parallel, but more 

 especially is this desirable when wet preparations are to be exhibited. 

 The case is of considerable depth, but, since there are no large 

 specimens in the series, the facia is brought forward quite close to the 

 glass, and every specimen is thus within convenient distance of the 

 spectator. (Plate xix.) 



The preparations are arranged in eleven upright columns, the 

 broadest of which is ten inches and the narrowest five inches in 

 width. The columns are marked off from one another by narrow 

 strips of polished mahogany, and in each column the four orders of 

 Amphibia are separated in a similar manner. 



The tablets on which the specimens are mounted are covered 

 with a neutral grey paper, and, since osteological preparations show 

 to so much better advantage on a dark background, these are placed 

 on rectangular black papers cut to such a size as to leave a f-inch 

 grey border. The value of the grey border in relieving what would 

 otherwise be a continuous black surface cannot be over-estimated ; 

 the total effect is not only more attractive and pleasing to the eye, but 

 that feeling of depression which a large expanse of black surface 

 engenders is removed. 



Since the study of morphology involves palaeontology quite as 

 much as zoology, as regards those parts of the body which can be 

 preserved to us as fossils, the remains of extinct Amphibia are treated 

 in exactly the same manner as the hard parts of their living relatives. 



The collection owes a great deal of its completeness to the fact 

 that the practical difficulties of exhibiting spirit specimens and dried 

 preparations side by side have been overcome in a manner which, if 

 not perfect, marks a distinct advance on the methods of museum 

 exposition previously in vogue. The distressing refraction which was 

 so great a disadvantage in the use of oval or cylindrical bottles is 

 avoided by the employment of rectangular glass jars, which are 

 manufactured now far more neatly than when, not many years ago, 

 they were first introduced into museums. The preservative employed 

 is in all cases 70 per cent, alcohol. Great advantages have recently 

 been claimed for an aqueous solution of formic aldehyd, but having 

 regard to the chemical instability of this substance it is deemed 

 prudent to wait, before employing it as a preservative, until more is 

 known about its behaviour when exposed for any length of time to 

 bright sunlight. The background of each spirit specimen is white or 

 black according to the predominance of dark or light colours in the 

 dissection. Specimens dissected from the dorsal or from the ventral 

 surface are mounted with the snout uppermost, but in side dissections 

 the head points to the left. 



Every specimen is exhibited for a definite purpose, which is 

 explained either in the label of the preparation or in that of the series 

 of which it forms part. In the dry preparations each of the more 



