PREFACE. 



THE description of the immature state of the species belonging to 

 the subfamily Gomphina is to be followed by that of the other five 

 subfamilies of the interesting family of the Odonata. The materials in 

 the collection of the Museum of Comparative Zoology are very rich, 

 as is well shown by the Gomphina. Up to this time two species only 

 have been published, both from Europe ; now seventeen are described, 

 viz. eleven from America, of which four are from South America, three 

 from Asia, and three from Europe. The relation of the larvae described 

 to the actually described images is, of course, very small. Baron De 

 Selys Longchamps, in Liege, describes in his monograph of the Gom- 

 phina, published with my collaboration, and in the two additions, one 

 hundred and seventy species, — just ten times more than the seventeen 

 immature species here published. But of the six legions of the Gom- 

 phina two only are not represented in this monograph, — Chlorogom- 

 phus with one sj^ecies from Japan, and Petalura with three species from 

 New Holland and North America. 



Of the species described, only four are raised and identified beyond 

 any doubt, viz. G. vulgatissimus, by Dr. F. Brauer; M. spiniceps, by Mr. Fr. 

 G. Sanborn; H. brevisti/lus, by the late Dr. T. W. Harris; 0. bideniatus, by 

 Dr. F. Brauer. All the others are determined by exclusion or supposi- 

 tion, and some of them more or less doubtfully. The general character 

 of the subfamily will be better given with the publication of the nearly 

 related ^schnina. 



I am responsible in this monograph for the determination of the 

 species, as Mr. L. Cabot had not studied the imago before, and for the 

 .synopsis, taken from his descriptions. 



H. A. HAGEN. 



July 5, 1871. 



