FOREIGN GENERA OF DELS. 
103 
attention, for it is opposed to the economy of nature 
that there should exist any without functions of essential 
usefulness, making them important elements in her har¬ 
monious order and necessary to her due course, irre¬ 
spective of the instruction to be derived from the study 
of the manifold varieties of structure, which unquestion¬ 
ably point to distinguishing peculiarities of habits. 
In the true bees the division of the Dasygasters presents 
the fewest differing generic forms: the Nudipedes and 
Scopulipedes exhibit more numerous varieties, the pre¬ 
ponderance being in favour of the pollen-collecting bees 
(the latter), although the cuckoo bees (the Nudipedes) 
are very abundant, and taken en masse, are certainly the 
handsomest. If it be absolutely the case that there are 
no parasites amongst the Andrenidce, this subfamily will 
add very largely to the exotic pollinigerous majority, 
which thereby becomes extensively subservient to the 
fruition of the vegetable kingdom. 
Those bees which are exclusively inter- or sub-tropical, 
seem furnished with larger capacities for fulfilling the 
special mission to which the family is appointed/ Their 
pollinigerous and honey-collecting organs are peculiarly 
adapted both to the structure and luxuriance of the 
superb vegetation of those regions, and to which they 
seem distinctly limited. But that they are not con¬ 
sidered equivalent to the entire demand of the profuse 
bloom everywhere abounding, may be concluded from 
the tropical range and distribution of many of our 
northern forms. Thus, whilst the flora of those climates 
is strictly circumscribed in its diffusion, its fauna, dis- 
tinctly in the class of insects, and especially in the family 
of bees, is very considerably less limited in extension. 
The exotic genera of bees which are peculiarly notice- 
