of the Oil Beetle, Meloe. 355 



tion from a carnivorous to a truly vegetable-feeding insect, the transition itself 

 being in reality gradual, like the change which takes place in the form of its 

 manducatory organs. The manner in which the change in the structure of 

 these parts is effected, and the slender, jointed, unguiculated, pediform organ 

 of the young larva, fitted only for piercing and for prehension, is altered to 

 the short, obtuse, and powerful jaw, is by the relative shortening, consolida- 

 tion, and anchylosis of the coxal, femoral, and tibial divisions of the pediform 

 mandible, whilst the long claw-like and acute apex is deciduated and entirely 

 thrown off as a portion of the tegument at the next change of skin. This 

 relative shortening is continued throughout the metamorphoses, and in this 

 way the organ is gradually more and more altered in structure (fig. 9), is fitted 

 for a new function, and is adapted for a complete change in the habits of the 

 imago. 



A general correspondence in structure thus seems to indicate similar corre- 

 spondence in habit and function. Those families of insects which are most 

 nearly allied in organization approach the most nearly to each other in their 

 economy. But they differ from each other in the divergence of their particu- 

 lar habits or instincts from one general character, according as the structures 

 which minister to those habits or instincts depart from the common type of 

 formation. The larva of Sitaris, in the general conformation of its body, re- 

 sembles that o{ Meloe, and both, as we have seen, are parasitic in their habits 

 in the nests of the same genus of insects ; but they differ in their special eco- 

 nomy as well as in particular details of structure. All we yet know of the habits 

 oi Horia shows that this family also is parasitic in its larva state in the nests 

 of the carpenter-bee. The perfect insect has long been known to be allied 

 in general structure to the perfect Meloe, and I have little doubt that it 

 approaches closely to that of Meloe and Sitaris in the early stage of its larva. 

 The drawing given by the Rev. L. Guilding of the advanced stage of the larva 

 oi Horia, and the fact that Mr. Guilding's specimen has six short legs, so 

 closely agree with the advanced stage oi Meloe, that we may fairly regard the 

 general form of the larva in the earlier stages of these two insects as similar, 

 and conclude that Horia, Sitaris and Meloe all at first are parasitic on the 

 bee-larva. 



VOL. XX. 3 A 



