Mr. Westwood on the osada?it genus Nycteribia, 393 



being exclusively confined to a parasitic existence on that equally 

 anomalous group, the Chiroptera among the Mammalia, 



Notwithstanding the comparatively unattractive appearance of the 

 insects of this genus, the singular peculiarities of their structure have 

 drawn upon them the attention of Latreille, Hermann, E|r. Leach, 

 M. Leon Dufour, and Mr. Curtis, who have severally contributed 

 much to the general stock of information respecting them. But the 

 minuteness of the objects themselves, their unfitness for accurate ex- 

 amination when dried and shrivelled as specimens usually are in cabi- 

 nets, their comparative rarity, and other causes, have rendered the 

 descriptions of those distinguished entomologists in some instances 

 unsatisfactory ; and it is with the view of fully elucidating the or- 

 ganization of the genus and of adding to its history such facts as he 

 has been enabled to ascertain, that Mr. Westwood offers to the So- 

 ciety his account of Nycteribia, to which he adds a Synopsis of the 

 whole of the species that have hitherto been observed, including the 

 characters of several not hitherto described. He enumerates the 

 sources from whence his materials have been derived ; and then pro- 

 ceeds to describe in great detail the structure of a new species brought 

 from Dukhun by Col. Sykes, — a species peculiarly adapted for the 

 purpose, both on account of its comparatively large size, 24- lines in 

 length, and of the fitness of the individuals for minute examination 

 owing to their having been preserved in spirit. Of this species he has 

 examined three individuals, all of which are females in different stages 

 of gestation. From the abdomen of the one which was most ad- 

 vanced Mr. Westwood extracted without difficulty a hard organized 

 white mass, nearly as large as the abdomen itself, of an oval form, 

 with traces of five articulations on the sides of the body, and having 

 at its broader end three small circular spots placed in a triangle, 

 with two smaller ones seated at a greater distance from them. That 

 this was the young of the Nycteribia in its pupa state cannot, he 

 conceives, be doubted : and it may consequently be regarded as 

 proved that these insects are pupiparous, as has indeed been conjec- 

 tured from their evident connexion with the Hippoboscida. 



The whole of the external organization of Col. Sykes's Nycteribia 

 is described by Mr. Westwood in the greatest detail, and with 

 continual references to those portions of the descriptions published 

 by his predecessors, which are either vague, or incorrect, or in which 

 they are contradictory to each other. The principal points which he 

 has endeavoured to elucidate, in addition to the transformations which 

 these insects undergo, are the distinction of the sexes, and conse- 

 quently the sexual characters and the different organization of the 

 abdomen in the sexes ; the structure of the mouth, antennce, and eyes ; 

 the separation of the metasternum and the abdomen ; the situation and 

 construction of the spiracles ; and the nature of the serrated organs 

 between the base of the anterior and intermediate legs. The sexual 

 distinctions appear especially to have been misunderstood, and the au- 

 thor takes great pains to explain them in each of the species respec- 

 tively which he has been enabled satisfactorily to examine. 



Mr. Westwood concludes his Paper by a Synopsis of the Species 

 Third Scries, Vol. 6. No. 35. May 1835. 3 E 



