The whole of the cibarial apparatus, or trophi, is always complete in all its constituent parts throughout the _Andrenidæ_; and it is only with _Ceratina_, in the group of _scopuliped Apidæ_, that it begins to show the tendency it has to abnormal deficiencies, by the paraglossæ, in that genus, being obsolete. This characteristic, then, exhibits itself in the _Nudipedes_ with two submarginal cells who are parasitical upon the _Dasygasters_, in whom also the maxillary palpi participate in a deficiency in the authentic number of their joints, whilst in _Apis_ both maxillary palpi and paraglossæ are unapparent. This shows that the numerical completion of the organs of the mouth have nothing to do with the qualifications of the creature, the best endowed in other respects being thus curtailed, the final cause of which is not yet understood. The shape of the tongue itself thus separates the _Andrenidæ_ into three well-defined divisions readily perceptible. These, as I have just observed with respect to the differences in the mode of closing the oral apparatus in both cases, yield no clue to economy and habits, for which observation must supervene to illustrate it. This, patiently carried out, is very desirable, as it is still in discussion whether, notwithstanding the elucidation structure affords, _Prosopis_ and _Sphecodes_ are or are not parasitical. Structure says they are, for, like the cuckoo-bees forming the group _Nudipedes_ in the _Apidæ_, they are destitute of the requisite apparatus for collecting pollen. Mr. Kirby, however, gives direct testimony in favour of _Sphecodes_ being a burrower, in the case of which bee it ought not to be a matter of much difficulty to determine, for on sandy plateaus I have occasionally found it very abundant, especially where there was ragwort (_Senecio_) in flower in the vicinity, to which the males resorted; but being at the time more intent on other matters, I neglected the opportunity. Other observers concur with Mr. Kirby as regards _Sphecodes_, and also say as much for _Prosopis_ (better known as _Hylæus_). I strongly incline to the opinion enunciated by Latreille and Le Pelletier de St. Fargeau, that they are parasites. My opinion is based upon peculiarities in them other than, although strengthened by, the negative characteristic of absence of polliniferous organs. A negative cannot be proved, it is true, yet what has been positively asserted may as certainly result either from defective observation, or from too strong a desire to find no parasites among the _Andrenidæ_. My reasons occur elsewhere in this work, and I need not repeat them. It is still an open question, and the young entomologist, if entering the arena unprepossessed, might win his spurs in determining it. It would be well worth the trouble of attending to for those who have leisure, and if decided in favour of the independency of these genera, which must be corroborated by a plurality