( ciii ) 



Larvae of the following species, Cossiis cossics, Lasiocampa 

 rubi, L. quercus and Smerinthus populi, had been sub- 

 mitted to air pressures of from 10 to 30 atmospheres for 

 periods up to 2 hours and 40 minutes. In all the experi- 

 ments decompression was effected in a few seconds. No ill 

 effects resulted and two specimens, which were kept under 

 observation, pupated and emerged normally. The fatal effect 

 of such exposure upon Vertebrata was demonstrated on frogs 

 used as controls. 



Although, therefoi-e, larvse were immune from decom- 

 pression lesions they appeared to be nearly as susceptible to 

 oxygen poisoning as frogs. Two larvfe of Smerinthus popidi 

 were affected by exposui-e to 16 atmospheres of pure oxygen 

 in the same time as a control frog. 



If larvpe were allowed to feed while under pressure, the air 

 swallowed with the food plant would produce fatal lesions on 

 decompression. A larva of L. quercus, placed in the pressure 

 chamber at 11.25 a.m., together with some food plant, much 

 of which was consumed, appeared to be killed instantly by 

 decompression at 11.40; the gut being enormously distended 

 with semi-digested leaves and air-bubbles. 



A discussion followed in which Dr. F. A. Dixey and 

 other Fellows joined. 



Dr. T. A. Chapman exhibited a long series of HasUda 

 hyerana, Mill., bred this year from larvfe collected at Hyeres ; 

 and a diagrammatic map of the neighbourhood to explain 

 the distribution of the moth in that area. The moths 

 consisted of about two hundred and fifty specimens from 

 " Les Maures," the low hills behind Hyeres, nearly 50 per 

 cent, of which were melanic ; and about a hundred and 

 seventy from " La Plage," the coast nearest to Hyeres ; but 

 these contained only about 14 per cent, of melanic forms. 



" The former area (Les Maures)," said the Exhibitor, " would 

 appear to have been searched in vain fifty years ago by 

 Milli^re, who found the insect, however, at the Hermitage 

 ( = Costebelle), an area cut off from Les Maures by perhaps a 

 mile and a half of country not habitable by //. hyerana, but 

 probably continuous with the La Plage habitat. Hence it is 

 not improbable that the insect had at that date recently 



