of the Amazon Valley. 41 



cient to give a lucid view of the contents of this greatly aug- 

 mented family of insects. Within each of the tribes the diversity 

 of forms is so great that it has become absolutely necessary to 

 subdivide them, and ascertain at the same time the relations of 

 the subdivisions to each other. I was therefore unwilling to 

 publish descriptions of the new forms without first attempting 

 to class the whole in natural groups, as well as to define better 

 the already known genera. A mere succession of a multitude of 

 genera treated in an isolated manner, without indications of the 

 affinities which link them together (such, in fact, as has been 

 given hitherto in works on the family), could lead to no useful 

 scientific results. 



No general treatise has appeared on this subject (until within 

 the last few months) since the imperfect one of Audinet- Serville 

 in 1832-4. In this work the genera are very insufficiently charac- 

 terized, often from the examination of a single species. Shortly 

 afterwards appeared the third edition of the Catalogue of Count 

 Dejean, in which a great number of new genera were introduced 

 without characters at all. On the uncertain foundation, how- 

 ever, of these two works, a vast number of new species and ge- 

 nera have been published, many of the former being referred, in 

 a most loose and unsatisfactory manner, to the uncharacterized 

 genera of Dejean. The want of a good monograph, such as 

 exists on many other families of Coleoptera, has long been felt. 

 Faunists, in treating of the family in their special works, and 

 authors of the numerous works on the zoology of voyages, public 

 and private, have been obliged to describe great numbers of new 

 genera and species without reference to a reliable general classi- 

 fication ; besides which, many Coleopterists to whom the family 

 is attractive on account of the great beauty and variety of its 

 forms, have continually published isolated descriptions of new 

 species and genera, and this in every variety of natural-history 

 periodical, and in almost every European language. In this 

 way at length about 820 genera and 4500 species have been in- 

 troduced into the science, a very large portion of them without 

 proper indications of their place in the system. 



The general treatise upon the Longicornes which I have 

 alluded to above as having appeared very lately is by M. J. 

 Thomson of Paris, and entitled 'Essai d'une Classification de la 

 Famille des Cerambycides/ It is founded on a previous special 

 work on the North American Longicornes published by Dr. Le- 

 conte in 1852, called ' An Attempt to classify the Longicorn 

 Coleoptera of America north of Mexico/ The latter essay was a 

 great step in advance, as it entirely remodelled the previous 

 knowledge on the subject, and took into account many parts of 

 the structure of these insects which were left unheeded by pre- 



