Anatomy and Development of Scorpions. 125 



Urodacus novce-hollandue, Pet. (PI. IX. fig3. 3 a~d.) 



The embryos of this form in my possession are in an 

 advanced stage of development, the eyes, limbs, &c. being all 

 well formed; they measure about 12 millim. in length and 

 are markedly cylindrical. The appendix is short and there 

 is a well-marked thickened portion at the top of the diver- 

 ticulum. Kemoved from the follicle the embryo appears as 

 in figs. '6 b & c. The chelicera? project straight out in front 

 and are of considerable length, terminating in a cup placed 

 towards the inner side. From this cup an incomplete groove 

 seems to run between the two chelicerse down towards the 

 mouth. This groove is partly closed in at its posterior end 

 by processes from the basal joints of the chelas (fig. 3 c). 

 The central cord of the appendix terminates close to the distal 

 end of the chelicerse. 



The chelae have their elbows well forward in front of the 

 carapace and project into a fold of the surrounding diverticu- 

 lum, as is indicated by the dotted line in fig. 3 b. The inside 

 of this fold is lined with apparently actively secreting cells. 

 Fig. 3<i is a section across just above the elbows of the chelse 

 and shows the structure of this part of the diverticulum and' 

 also that.of the lower part of the appendix and the chelicerte. 

 The secretion from these cells at the upper end of the diver- 

 ticulum is probably for the most part absorbed by the mouth, 

 there being nothing in the structure of the chelaj to indicate 

 absorption as one of their functions. Secretion by the top of 

 the diverticulum is, I think, a somewhat primitive mode 

 among these katoikogenic forms, as it is only continuing to a 

 somewhat later stage the mode by which the embryo is 

 nourished in its early stages before the mouth is formed. 

 The arrangement of the chelicer^ leads towards the state of 

 affairs we find in Ischnurus, while the method adopted by 

 Hormurus derives itself from the secreting upper part of the 

 diverticulum. 



Ischnurus ochropus, Koch. (PI. IX. figs. Aa-e.) 



The embryos of Ischmirus are in an advanced stage and 

 measure 10 millim. in length, while the appendix at the distal 

 end of the follicle measures about 3 millim. The form of the 

 appendix differs from that of Scorpio in that it is not spirally 

 twisted on itself and has a distinct dilatation on it. On 

 removing the follicle, which can be done without much diffi- 

 culty, the first point that strikes one is the hairiness of the 

 embryo. The segments behind the carapace, which are 



