142 Bibliographical Notices. 



value of such labours is not duly appreciated in this country ; yet it 

 is an incontrovertible fact, that until differences are accurately de- 

 fined we cannot record even facts with certainty ; and unless we 

 submit to a careful investigation at least of the external anatomy, 

 the greatest errors may be committed. But until Natural History is 

 considered worthy to form a class in our schools, it is to be feared 

 that little attention will be paid to Entomology, although it is one of 

 the most imj^ortant branches of Zoology. 



Amongst the autliors alluded to is Vander Linden, who in 1825 

 published at Brussels his ' Monograjihia Libellulinarum Europsearum 

 Specimen,' which, although a limited production,was very acceptable; 

 in the same year the ' Horse Entomologicae ' of Toussaint de Char- 

 pentier put us in possession of a more extensive Monograph of the 

 Libellulidse of Europe, with a 4to plate exhibiting specific characters 

 from the structure of the anal appendages, and this led to the pro- 

 duction of the best work that has yet appeared upon the family, the 

 ' Monographic des Libellulidees d'Europe,' par M. De Selys Long- 

 champs, which was preceded in 1837 by a ' Tableau des Libellulines 

 de la Belgique,' containing a systematic list of the species with their 

 localities, and the characters of two new ones, Petalura fiavipes and 

 Agrion aurantiaca. 



The ' Monograph' exhibits a general view of the external anatomy 

 of the Dragon-flies, in oi'der to refer correctly to the relative position 

 of the various members ; but one of the most useful parts is the se- 

 ries of Synoptic Tables : the first gives the genera, comprising Li- 

 bellula, Libella, Cordulia, Lindenia, Gomplius, Cordulegaster, JEschna, 

 Anux, Calepteryx, Lestes, Sympecma and Agrion, of which the three 

 following are not generally known. 



Libella, De Selys, distinguished from Cordulia by the anal border 

 of the inferior wings being rounded in both sexes. 



Lindenia, De Haun, is characterized bj^ an elevated tubercle be- 

 fore the eyes, which are globose, whereas in Gomphus the space is 

 flat and the eyes compressed. 



Sympecma, Charp., is separated from Lestes by its wings being 

 elevated in repose, and from Agrion by its elongated parastigma. 



There are also three synoptic tables exhibiting the essential cha- 

 racters of all the species, amounting to 61, of which there are like- 

 wise more ample descriptions, with the synonyms, localities, etc. 



The dimensions of all the species of the Libellulidse in a tabular 

 form is also a novel feature, and adds to the facility of identifying a 

 form, as this family varies less in the size of the sexes and of indi- 

 viduals of the same species than most others. 



A disquisition follows upon the discoidal triangular cells in the 

 wings, which vary in the different groups ; they were first noticed 

 by M. Vander Hoeven, and this section embraces some exotic ge- 

 nera. 



The ' Conspectus Specierum,' in which Charpentier's genus Pla- 

 tycnemis is characterized, to receive the species platyjjoda, is drawn 

 up with great care, and completes M. De Selys's work ; and there are 



