By a ‘type’ is meant the original specimen to which any generic or specific name was first assigned. Subsequent observers in examining specimens which agree in general characters with an already described form, often notice differences which may indicate a new species, may be only due to incomplete description, or to the imperfect state of preservation of the type. In order to determine these points, it is necessary for them to see the actual fossil, which the author of the species had before him, when he wrote his description.

The importance of preserving and distinctly marking figured and described specimens, has only of late years been generally realised. A committee of the British Association reported upon the subject last year. In the Woodwardian Museum such specimens have been mounted on tablets of a special colour,—at first pink was used, but now blue, a more stable colour is being substituted. The plan of exhibiting all the types by themselves, on the top of the cabinets was tried, and, except where they are mounted on coloured tablets, this method can be recommended, as in every museum of importance, inferior specimens are continually being replaced by better ones, and thus the type, which is sometimes a poor specimen may perhaps get lost sight of. As soon however as the types were mounted on tablets of a conspicuous colour, we found that they could be safely put into their proper places in the series, and that it was better to display on the top of the cabinets those specimens which best showed generic and specific characters, and were thus of greatest educational value and general interest.