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XXX. On Nycteribia, a Genus of Wingless Insects. By J. O. Westwoop, Esq., 
F.L.S., &c. Communicated by the Secretary. 
Read November 25, 1834. 
In every group of animated nature, even down to the ranks of families and» genera, 
there exists a certain number of objects (generally of limited extent) which, from the 
anomalous character of their organization with reference to that of the group to which 
they naturally belong, have not ceased to perplex the systematist as to their true 
situation. If this has been the case after the real nature of their organization has 
been made known, the difficulty has been far greater when, unaided by the light of 
minute analysis, the naturalist has contented himself with a rapid primd facie exami- 
nation. 
Thus, if we look at the great divisions of the Animal Kingdom, we find the Tunicata, 
Cephalopoda, Zoanthida, Cirripeda, and Annelida affording examples of such groups. 
If we descend a step, we find the Pycnogonida, Oniscida, Stomapoda, Nycteribia, and 
the Trilobites oscillating amongst the classes of the Annulose subkingdom; while in 
like manner the Strepsiptera and Dermaptera, and the families Thripside and Pulicide 
amongst the orders of the Ptilota, and the genera Zoea, Nebalia, Hippa, Mysis, Limulus, 
Nymphon, Galeodes, &c. amongst those of the Aptera, have afforded endless opportu- 
nities for exercising the ingenuity of systematists. To carry the observation still lower 
among the families of an order, I need only refer to such genera as Omophron, Urania, 
Xyela, Trictenotoma, Acentropus, &c. 
With respect to such groups, it is to be noticed that they seem to be generally cha- 
racterized not only by their limited extent, but also by the comparative smallness and 
rarity of the objects composing them; and that they appear to constitute a series of 
stepping-stones whereby the transition from the structure of one group to that of the 
adjoining ones is effected, many of them, in fact, forming the osculant groups of the 
‘Hore Entomologice’. Another peculiarity seems to consist in the generally unat- 
tractive appearance of the objects of which they are composed, which has caused them 
(notwithstanding the great interest possessed by them on account of the peculiarity of 
their characters) to be comparatively neglected by the majority of authors. 
Among these groups, perhaps no more striking instance could be adduced than the 
genus Nycteribia, Latr., inasmuch as we here find a single genus, considered as oscu- 
lant, not between the families, or even the orders of a class, but between two of the 
classes themselves of the Annulose subkingdom ; thus, while Hermann, in his ‘ Mémoire 
VOL. I. 20 
