o('. 



Platk IV. 



Fig. 1. Longitudinal section of a single omniatidiuni. 

 (Drawn with the camera liicida.) (ace. con.) 

 accessory cone; (J). in.) basement membrane; 

 {con.) cone; {corn, cut.) corneal cuticula ; {nuc. 

 con.) nucleus of cone cell; {nuc. ret.) nucleus of 

 the retinular cell ; (oj). n. f .) optic nerve fibre ; 

 [pfl.) pigment; {[-></. c.) pigment cell; {ret.) 

 retinular cell; ('■/;.) rhabdomere ; (s-cJii/p.) 

 sub-corneal hypodermal cell. 



Fig. 2. Transverse section of ommatidium showing the 

 six retinulae cells and their rhabdomeres. 



Fig. 3. Longitudinal section through the cuticle of a 

 segment of the fiagella of the second pair of 

 antennae to show a sensory bristle and its 

 nerve supply. (ch.) thick layer of (diitin ; 

 (cfla.) cuticula; i/iyp.) hypodermal layer; (n-f.) 

 nerve fibrils; {.^i.h.) sensory bristle; (.sVk) sheath 

 of sensory bristle. 



Fig. 4. (ienerative organs of the male. (t.) testes ; 

 opening into {j-'.d.) the vas deferens, which 

 opens externally by the styliform a})pendages 

 {st. a p.). 



Fig. 5. A collection of ' sperm-colonies ' as they are 

 found in the vas deferens, in the cohesive 

 substance secreted by the latter. 



Fig. 0. Early stage in the development of the q^\i, 

 showing the cleavage of the germ disc into the 

 two antero-lateral mesoderm fuiuhunents [(i.m.) 

 and the median jiosteiior endoderm fundament 



{end.). 



