58k MODERN CLASSIFICATION OF INSECTS. 
dinis). In others, the wings and balancers are entirely wanting, the 
legs are short and strong, and terminated by very powerful denticu- 
lated claws (jig. 133. 12.). 
The abdomen is covered with a continuous membrane, capable of 
great distension, which occurs in the females, the larvae hatching and 
being nourished in that situation until they have assumed the pupa 
state, when each is deposited in the shape of a soft white roundish 
egg notched at one end, without any trace of articulation, and nearly 
as large as the abdomen of the parent fly (fig. 133. 9.). Subsequently 
this puparium becomes hard, and dark coloured, and within this pupa- 
rium the real pupa (jig. 133.10.) is found, and from which the fly 
escapes by scaling off the notched extremity of the case. Although 
these insects are furnished with a pair of remarkable ovaries, their 
progeny consists but of a single pupa, after the exclusion of which 
the abdomen becomes shrivelled and contracted. 
Mr. MacLeay considers that the Pupipara effect the passage be- 
tween the classes of Haustellata and Arachnida. Mr. Curtis, however, 
in his observations, has endeavoured to show that a more natural tran- 
sition is effected between the Mandibulata and Arachnida, by means 
of the voracious Cicindelidze and the spiders. The instances which 
he has adduced in support of this view, appear to me to be remote 
analogies, whilst, on the other hand, the connexion between the Hip- 
poboscide and Nycteribiide, and certain Arachnida is so strong as 
to become almost an affinity. The latter, it is true, are not the 
typical Arachnida, or Spiders, as might be imagined from the verna- 
cular French name given to these insects, expressive of their resem- 
blance to spiders —“ mouches araignées,” but to others which 
have not hitherto been regarded as affording so strong a relationship, 
namely, the Acarideous Arachnida or Ticks. This relationship is so 
strong, as regards habits and economy, that there is no wonder that 
one of the Hippoboscidz should be called the Sheep-tick. Whilst, 
if we look at the construction of the mouth, we have precisely the 
same number of organs, the external pair of which are exactly similar 
to the rostriform plates of the Hippoboscide. ( Vide M. Audouin’s 
admirable paper, in the Ann. Se. Nat. tom. xxv. pl. 14.) 
These insects vary greatly in the animals they inhabit. The spe- 
cies of Ornithomyia, Stenepteryx (remarkable for the narrowness of 
its wings), and Oxypterum are parasitic upon various kinds of birds 
(see Curtis); those of Hippobosca upon quadrupeds, especially the 
