490 THE ENTOMOLOGIST. 



differs from it in having two terminal lobes, one on each side, 

 of a widely-shaped oblong. 



The substance of the brain appears to be amorphous, and 

 I could not with a power of 700 linear detect the slightest 

 indication of convoluted structure. Two pairs of nerves are 

 distinctly to be seen passing from the cerebrum. The first 

 pair are the optic nerves, which originate at the lateral 

 margin of each mass of the cerebrum from a small conical 

 mass, the base of which is on the surface of the brain-lobe; 

 and from the apex of the cone the nerve proceeds in the form 

 of a small cylindrical thread, in a straight and tense line, to 

 the base of the eye, where it expands into a cone of attach- 

 ment very similar in form and size to that from which it 

 emanates. The diameter of the base of the cone measured 

 •jy-^o inch, the extreme length of the optic nerve is y^ inch, 

 and the nerve at about equal distances from its terminations 

 measured T-jVr "^ch in diameter. 



The second pair of nerves passing from the cerebrum are 

 the antennal ones. They originate from conical bases very 

 similar in form and size to those of the optic nerves, from the 

 fore part of the margins of the brain-lobes opposite to the 

 basal joints of the antennae, and pass beneath the muscles in 

 a meandering course into the antennae at about the centre of 

 the basal joints. In the right antenna, in which the nerve is 

 most distinct, it pursues its course in a direction inclined to 

 its right side until it reaches the base of the second joint, 

 through which it passes in a diagonal direction to the left side 

 of the antenna, and thence continues its course as a flexible 

 thread until it reaches to about the middle of the terminal 

 joint of the organ, when it expands into the form of a large 

 conical mass, the broad base of which is closely attached to 

 the thin terminal membrane of the antenna, on the outer 

 surface of which there are numerous very minute hairs. The 

 terminations of the antennae are not like those of many other 

 insects ; they consist of a sunken area of thin membrane, 

 with a well-defined marginal ring surrounding and protecting 

 them from injury ; and it is on this thin circular area that the 

 minute terminal hairs are based. 



The antennal nerves are less than the optic ones; their 

 diameter at a slight distance below the commencement of the 

 expansion into the terminal cone measured ttttt inch, and 



