TRANSACTIONS OF THE ROYAL MICROSCO- 
PICAL SOCIETY. 
DESCRIPTION OF PLATE IX, 
Illustrating Professor Rymer Jones’s paper on the Structure 
and Metamorphosis of the Larva of Corethra plumicornis. 
Fig. 
1. — Larva of Corethra plumicornis representing the general arrangement 
of the viscera, and the position of the air-vesicles, sketched under the 
compressor, and magnified sixty diameters. 
2. — Pupa of Corethra plumicornis as seen under the compressor shortly 
after its change from the larva condition. The air-vesicles have 
disappeared, the anterior pair having been converted into the respi- 
ratory tubes — O' O'. The now largely developed tracheal system 
seems to be entirely derived from the disruption of the two pairs of 
air-vesicles, the lacerated remains of which may be seen scattered 
throughout the cavity of the body and adhering in the shape of 
small patches of black pigment to the walls of the lateral tracheae. 
The ganglionic nervous system of the dorsal vessel is largely developed, 
and the masses composing the ventral series of ganglia of great pro- 
portionate dimensions. From the opacity of the thoracic region it 
was impossible to see whether any changes had occurred in the con- 
1 dition of the proventriculus and muscular gizzard. 
3. — Represents the head and apparatus of jaws of the larva of Corethra 
plumicornis as seen uuder the compressor, magnified about 200 
diameters. The proventriculus is inverted and protruded from the 
mouth together with the muscular gizzard /, and the narrow tube g t 
whereby the latter viscus originally communicated with the ventricular 
portion of the alimentary canal; a nervous plexus, and a few gan- 
glionic centres are seen in the muscular walls of the proventriculus. 
The same letters of reference indicate corresponding parts in all the 
three figures. 
1. — 1st pair of oral appendages. 
2. — 2nd pair of ditto 
3 — 3rd pair of ditto 
4. — 4th pair of ditto 
5. -— 5th pair of ditto 
