Dr. J. E. Gray on the i/enas Assiminia. 423 



divisions as more than assemblages formed for general conveni- 

 ence, and not having any absolute existence in nature. I think 

 this is sufficiently proved by the facts, — first, that there still exist, 

 or have formerly existed, some species M-hich are confessedly 

 intermediate between two or more of all these divisions ; and 

 secondly, that species which are placed together even in the 

 smallest groups frequently present some character which shows 

 either an analogical or a special afiinity with the species of several 

 other groups. Naturalists have availed themselves of this 

 method of grouping animals together for several reasons, but 

 principally for the following purposes : — 



1. To abbreviate the accounts of the different species or kinds. 



2. To enable students, by the examination of a few striking 

 characters, to discover the name of the animal under examina- 

 tion. 



3. To enable them to show the relations which the different 

 groups bear to each other and to the general scheme of creation. 



If this course were not adopted, it would be necessary, in the 

 description of every animal, to describe at length every charac- 

 teristic of form, structure and habit, even those which are com- 

 mon to many thousands of kinds, instead of mentioning only 

 those which distinguish it from the few most nearly allied to it ; 

 repeating under every species what are now condensed in the 

 characters of the genera, families, orders and classes of animals, 

 which are as a matter of course considered to be common to all 

 the animals which make up each of these groups, and are under- 

 stood to be present in each of the species referred to them. It 

 is a further advantage of this system of classification by groups, 

 that the minute attention requisite to make out the characters 

 of these groups produces also great minuteness and nicety of 

 observation, which otherwise might not exist. In the same 

 manner, if this system of division did not exist, whereby to lessen 

 the labour of discovering the name of any animal, we should 

 have to go through the interminable operation of reading with- 

 out order the full descriptions of all the animals which have ever 

 been described, instead of first looking for the class, order, 

 family and genus of the species, and then comparing it with the 

 descriptions of the few species that compose the smaller groups, 

 and are necessarily most allied to it. 



It has therefore been the custom to consider that person as 

 the best zoologist, who has been able, by the extent of his studies 

 and the analytical power of his mind, to seize on and neatly de- 

 scribe the most invai'iable characters of the different groups of 

 species, as by so doing he enables other naturalists to acquire 

 with greater facility the knowledge they require ; and the accu- 

 racy and minuteness of his own studies ought also to enable him 



