Anatomy and Development of Scorpions. 127 



Hormurus australasice (Fabr.). (PI. IX. figs. 5 a, h.) 



This form was represented among mj specimens by some 

 moderately advanced embryos. The appendages are quite 

 distinct, but the eyes have not yet appeared. The diverticula 

 measure about 4 millim. in length and are peculiar in having 

 only a rudimentary appendix. The mode of nutrition is 

 quite peculiar. The chelicerse are short and in no respect 

 unusual in form, while the chelaj are unusually large. The 

 last joint of the chelae runs forward close to the middle line 

 and becomes associated with a mass of large granular cells, 

 which look more like young ova than anytliing else 

 (fig. 5 J, sc). The association is very close, as the chela is 

 drawn out into processes which run in among the cells. 

 These cells occupy a pocket on the ventral side of the top of 

 the diverticulum ; they differ from the secreting cells which 

 occupy a somewhat similar position in Urodacus in structure 

 and in being confined to the ventral side, instead of extending 

 as a collar all round. There is a dorsal pocket (fig. 5 b, sc'), 

 also apparently lined by secreting cells, which are more like 

 those ot Urodacus, but there seem to be no special absorptive 

 organs connected with it. 



Palamnceus Thorellii, Poc. (PI. IX. fig. 6.) 



This form agrees more closely with Scorpio and Opisth- 

 ophthalmus than with any of the others which I have examined. 

 The free segments grow out into dorsal processes, which in 

 the not very advanced stage in my possession are small, but 

 probably increase in size from this stage on. The chelicerte 

 are in the form of a pair of enormous conical structures, the 

 internal face of each being flattened and longitudinally grooved. 

 The grooves are lined with chitin, and in the tube formed by 

 the apposition of the grooves lies the central cord of the 

 appendix, which is masticated by the chelicerse. The enor- 

 mous size of these appendages is the most striking feature of 

 these embryos, and suggests that a mode of nourishment like 

 that in Urodacus was the earlier arrangement, and that this 

 chewing of the central cord is derived from it, Palamnceus 

 being in this case an intermediate form between Urodacus 

 and Scorpio, in which last the chelicera3 are much smaller 

 and more purely masticatory. 



If, now, we try to apply the above observations to the 

 classification of the order the result is as follows. I take as a 



