88 RICHARD EVANS. 



Pigs. 23 « and 23i (X 120).— These ligures represent two oblique sections 

 of the head of an embryo of the same age as the one sections of which are 

 shown in Figs. 22 a, b, and c. 



Fif. 23 a. — This figure shows a section passing dorsally near the median 

 plane, and venirally abuve the antenna and the eye. It shows the 

 archiccrebral lobe (a.lo.) above, and ihe three anterior brain lobes 

 below (lo}, lo?, lo?). In another section, quite close to the one repre- 

 sented, the continuation of the second and third lobes towards the 

 dorsal aspect, shown in the figure as one lobe, was distinctly divided 

 into two. The fourth lobe of the brain does not appear in the 

 section. 

 Fig. 23 h. — This figure shows a section passing through the head in such 

 a way as to cut the first, second, and third lobes {lo}, lo.-, lo.^) of the 

 brain on one side, and the fourth {lo}) on the other. It passes 

 through the first ventral organ {v. o.') of the left side, the second one 

 {v. 0.") of the right side, and the anterior portion of the third {v. o?"), 

 which is median in position and produced by the fusion of rudiments 

 from either side. 



Fig. 24 (x 50). — This figure represents an oblique section of the antero- 

 dorsal aspect of the brain of an embryo of the same age as the two previous 

 ones. It shows the small but distinct archiccrebral lobe {a. lo.) situated on 

 the left side of the median line; on the right side the section passes nearer to 

 the ventral aspect, and consequently cuts the first or antennal lobe of the 

 brain (/o.^). 



Figs. 25 a, 25 b, and 25 c ( X 170). — These figures represent three stages in 

 the development of the eye, which is derived from the ectodermal thickening 

 which gives rise to the brain. During all the stages of development the two 

 organs are connected to each other, the optic nerve being formed in situ. 



Figs. 2G a, 26 b, 26 c, 26 d, and 26 e. — The first four of these figures are dia- 

 grammatic representations of four stages in the development of the recep- 

 taculum ovorum and receptaculum seminis ; but the last shows the structure 

 and arrangement of these organs in the adult. The figures were obtained 

 from reconstructions made from series of sections, and have been modified so 

 far as to show the receptaculum ovorum lying in the same plane as Ihe recep- 

 taculum seminis, which seems never to be the case in nature. 



