98 MB. A, MUEEAY ON THE EAELT STAGES OF 



pounded are still well founded, alttougli some of the props on 

 whicli I rested them have to be withdrawn. In these circum- 

 stances I think I shall best perform my duty by simply laying 

 before the Society, at this the earliest opportunity, the observations 

 which lead me to think that I have been mistaken. 



To enable the Society to understand the point at issue, I must 

 crave their endurance whilst I recapitulate a little. 



Fellows are of course aware that OrtJiopteroits and Hemipterous 

 insects are characterized by what is called a semicomplete meta- 

 morphosis, that is, that they quit the egg, not in the shape of cater- 

 pillars, but nearly similar in form to the perfect insect, but with 

 some parts only partially developed ; that, after so appearing, they 

 at no time go into a dormant chrysalis state, but merely cast their 

 skin a certain number of times, after each of which the wings and 

 other parts of the insect make an advance towards their perfect 

 state. The first stage of these insects after their appearance out of 

 the egg has been treated by entomologists as a pecvdiar form of the 

 larva state, which Mr. Westwood has characterized as " homomor- 

 phous" or "monomorphous," from its resemblance to the perfect 

 insect after its first moultings; and when the wings begin to appear, 

 it was said to pass into the pupa state, and was called an active 

 nymph or pupa. Professor Owen, however, in his lectures on inver- 

 tebrate animals, pointed out that we ought not to look upon these 

 " homomorphous " larvae as true larvae, but that the true larval con- 

 dition was to be sought for in the egg. He stated that " these in- 

 sects" (the Orthopterous and Hemipterous) " are at one stage of 

 their development apodal and acephalous larvae, like the maggot of 

 the fly ; but, instead of quitting the egg in this stage,they are quickly 

 transformed into another, in which the head and rudimental tho- 

 racic feet are developed to the degree which characterizes the hex- 

 apod larvae of the Carabi and PetaJocera ; the thorax is next 

 defined, and the parts or appendages of the head are formed, at 

 which stage of development the young Orthopteran corresponds 

 with the hexapod antenniferous larva of the Meloe; but it differs 

 from all Coleopterous larvae in being inactive, and continuing in the 

 egg almost until all the proportions and characters of the mature 

 insect are acquired, save the wings." 



This statement was published in 1855, in the edition of Owen's 

 ' Invertebrate Animals,' when I happened to be engaged in writing 

 an account of a living specimen of the Leaf-insect {Fhyllium Scythe) 

 which was reared in that year in the Botanic Garden of Edin- 

 burgh ; and it suggested to me doubts as to the received mode of 

 explaining tlie phenomena of the development of these insects. 



