132 On the Ariatomy and Development of Scorpions. 



Scorpionidse. More evidence is wanted before we can judge 

 of the true relation of the various subfamilies of the Scor- 

 pionidse to each other ; but of those I have examined I am 

 inclined to place the Urodacini as the lowest. Tlie secretion 

 of nutritious material by a large section of the diverticulum 

 is what one would expect as the earlier form *. Distinctly 

 divergent lines from this point are shown by the Diplo- 

 centrini, Horniurini, Ischnurini, and Scorpionini. Further 

 material is still wanted before many of tiie forms can be 

 placed, and I have perhaps tried to base too much on a com- 

 paratively small number of observations. Doubtless the 

 criticism of other workers in the group will soon correct any 

 points in which I have erred. 



EXPLANATION OF PLATE IX. 



Lettering throughout. 



i. Chelicerae. iii.-vi. The walking-legs. 



ii. Chelae. c. c. Central cord of appendix. 



50 



Fig. 1. lurus. Transverse section of ovarian tube and egg, X y. 



Fig. 2. Hemiscorpius. A diverticulum with unfertilized e^^, X y. 



Fig. 3. Urodacus. 



3 a. Portion of ovarian tube with diverticulum containing em- 

 bryo, X \. 



3 b. Dorsal view of carapace and anterior appendages, X -y . The 



dotted line shows the way the walls of the appendix are 

 folded. 



3 c. Ventral view of the same. 



3rf. Transverse section through top of diverticulum and lower part 



of appendix, X y. 



Fig. 4. Ischnurus. 



4 a. Portion of ovarian tube and diverticulum containing embryo, 



2 

 X J. 



4 b. Dorsal view of embryo. The forward continuations of the 



chelicerae are broken short. X y. 



30 



4 c. One of the chelicer£e, X y. 



4 d. Section through appendix showing continuation forward of the 

 chelicerse (i.). The appendix, being curved, is cut in two 



* Is it possible that the loss of yolk was an adaptation to a climate 

 with shoxt summer and long winter, the provision of nourishment for the 

 embryo being thrown on the period when food was abundant instead of 

 yolky eggs being formed during hibernation ? 



