414 ME. H, M. BEENAED ON THE 



Plate XXXII. 



Fig. 1. A racquet-orgau, cleared in cedar-oil, showing the zonal arrangement of the interior tissues 

 nf, the radiating nerve-fibres (fig. 7) ; ret, the reticulum of nerve-fibres, connective tissue, 

 and blood-lacunae (figs. 5 and G, ret) ; ep, the folded epithelium (figs. 8 and 6, ep) ; we, row of 

 nerve-endings (figs. 2, 3, G). 



2. Section across the outer edge of racquet, showing the aperture of the nerve-endings (we) 



along a ridge {br). pr, protective ridge. 



3. Section showing the ridges folded together for the protection of the nerve endings. 



4. Surface view, showing thickness of the cuticle [cli) along the lateral edges of the racquet-organ 



and the apertures for fine sensory hairs on its surface («/«). 

 a. Section through the 2nd zone, fig. 1. ret, the reticulum of blood-lacunae, nerve-fibres cut 

 across, and tracheae ; ch, thick chitinogenous layer with outer glassy layer [y] ; b, blood- 

 spaces ; n, nerves cut transversely ; tr, tracheae. 



6. Optical section in the plane of the organ showing transition from the reticulum [ret) to the 



folded epithelium [ep) and from that to the outermost zone of nerve-endings [ne) [cf. fig. 1). 



7. Nerve-fibrils with long spindle-shaped nuclei from the innermost zone. 



8. Hypothetical transverse section, based upon a reconstruction of optical horizontal sections. 



The folded epithelium shown as a single layer, nf, nerve-fibres cut across ; b, the blood- 

 spaces. 



9. Surface view of the edge of a racquet of Rhax. The bolster-ridge [br] along which the nerve- 



endings open has evidently been turned down, while the protective fold [pr) has been bent 

 back and crushed down, thus exposing the bolster-ridge with the nerve-endings. 



10. Section of the tip of the first leg {Rhax), showing one of the rudimentary claws with two 

 tendons for its protrusion and retraction, the tendons moving in a clear blood-space ; on the 

 upperside, well protected by connective tissue, are great numbers of long bag-like sensory 

 cells, as shown in the next figure. 



11a. Appearance of the sensory cells of fig. 10; 11 b, the same at the proximal edge of the 

 sensory area. 



12. A thick longitudinal section of 1st leg of a small Galeodes, dorsal aspect, cleared in cedar- 



oil in order to examine the sensory cells in situ. They are seen down the centre as minute 

 dots (? apertures) on the cuticle, which ar-e in connection with peculiar sensory cells seen 

 through the cuticle (figs. 17 a, \7 b). The place of insertion of every hair is seen to be 

 surrounded by a special grouping of cells. 



13. The cell arrangement round the insertion of a large hair. The nerve-cells and secreting cells 



are protected by a wall surrounding the insertion of the hair distally. The next figure, — 



14.. Shows the section of a large sensory hair on the 1st leg of a Rhax, — the nerve-cells 

 and the secreting cells are protected by a kind of roof [ro) ; h, the hair ; rf, the radiating 

 fibres attached to its butt-end ; c, the canal connecting the chamber above the elastic (?) 

 fibres with the rest of the body ; se, the secreting cells, which are all thread-like, forming 

 a bag-like network in which the nuclei are suspended ; b, blood-cells ; n, a nerve-cell (?). 



15. Hair from the tip of the 1st leg of Rhax (figured 10) ; owing to its position, the bag-like 

 reticulum of secreting cells hangs straight down, whereas at the sides of the limb they slope 

 away in a proximal direction (as in fig. 14). 



IG. Large bag-like sensory cells, surrounded by connective tissue ; 16 a, the sensory process 

 passing through the cuticle. These cells occur along the edges of the dotted area in fig. 12. 



17. The appearance of the majority of the sensoi-y cells in the area shown in fig. 12 j 17 b, the 

 passage of the nerve-ending through the cuticle (diagrammatic). 



