208 BULLETIN OF THE MUSEUM OF COMPARATIVE ZOOLOGY. 



Fig. 17, the forty-first section, represents the wall of the deep (dorsal) end of the 



pocket cut tangentially. 

 Figs. 18 to 27 inclusive relate to the structure of the lateral eyes. Figs. 18 and 19 



are from preparations of adult eyes. 

 Fig. 18. The anterior face of a vertical a.xial section of the riglit eye (No. 2) ; 



compare PI. IV". Depigmented with a solution of potassic hydrate; 



stained with Grenadier's alcoholic borax-carmine. X 325. 

 Fig. 19. Anterior face of a frontal section. Partially depigmented with potassic 



hydrate ; stained with Kleinenberg's haematoxylin. X 475. 

 Figs. 20 to 27 inclusive give the structure of the eyes in young scorpions. Figs. 20 



and 21 are from material of the same age as Fig. 9. 

 Fig. 20. Anterior face of a vertical axial section of left eye (No. 3). The pigment 



is unafEected.^and no dye has been used. The edge of eye No. I is seen 



above. X 325. 

 Fig. 21. Anterior face of a vertical axial section of left eye depigmented in potassic 



hydrate and stained with Grenadier's alcoholic borax-carmine. X 325. 



PLATE IV. 



Figs. 22 to 27 inclusive are taken from the dorsal faces of a set of sections of the 

 youngest embryos at hand (of the same age as those from which Figs. 13 

 to 17 are taken). The sections have been depigmented with a solution 

 of potassic hydrate and stained in Grenadier's alcoholic borax-carmine. 

 X 325. The figures represent the left cluster of lateral eyes. Begin- 

 ning dorsally and proceeding ventrally, Fig. 22 is the first section, Fig. 

 23 the third, Fig. 24 tlie sixth. Fig. 25 the thirteenth, Fig. 26 the six- 

 teenth, and Fig. 27 the twenty -first. 



