AND DEVELOPMENT OF MELOE. 



183 



tions, changes which constitute it the true skeleton of the insect. The alterations which 

 the body undergoes in form are not accidental results of the actions of the muscles, 

 but depend in each species on definite wnvarying geometrical principles of force and rela- 

 tion. Portions of the tegument which give attachment to muscles are folded inwards in 

 the head and thorax, and becoming solidified constitute a rudimentary internal skeleton, 

 some parts of which merely give attachment to muscles, whilst others, as in the Verte- 

 brata, inclose and protect the nervous system. These I shall hereafter examine with the 

 dermo-skeleton of the imago. 



EXPLANATION OF THE PLATE. 



Tab. XX. 



Fig. 1 . The young Melo'e a few days after it has left the egg, highly magnified to show the structure of the 



organs of vision, a ; situation of the spiracles, b, b ; form of the tarsi, c, c, and caudal styles, d ; 



and internal muscular structure as seen by transmitted light. 

 Fig. 2. Inferior surface of the Melo'e larva, showing the structure of the pectoral and abdominal portion 



of the tegument. 

 Fig. 3. Melo'e larva seen from above by transmitted light, and showing its brain and alimentary canal. 

 Fig. 4. A portion of the tegument highly magnified, showing its hexagonal cellasform structure. 

 Fig. 5. One of the abdominal spiracles magnified, showing the tegumentary cells with irregular granular 



nuclei. 

 Fig. 6. One of the antennae, highly magnified. 



Fig. 7- A dermal spine or hair, originating from the nucleus of a single cell, highly magnified. 

 Fig. 8. Portion of tegument showing two layers of cells, the deeper-seated with their nuclei divided and 



in the course of reproduction. 

 Fig. 9. The large or thoracic spiracles. 

 Fig. 10. The eye of the larva, magnified, showing the cornea formed of tegumentary cells, with the single 



central ocellus. 

 Fig. 1 1 . View of the side of the head of the larva. 



Fig. 12. One of the tarsi, showing the articulated spines at the sides of the true claw. 

 Fig. 13. The full-grown or pseudo-larva, with its limbs reduced to tubercles preparatory to change to a 



nymph. 



Fig. 14. Skin of the full-grown larva, showing the microscopic hairs developed from the nuclei of cells. 

 Fig. 15. The nymph at the period of throwing off the pseudo-larva covering, with its limbs becoming 



rapidly enlarged. 

 fig. 16. The fully-formed nymph. 



