Dr. H. Woodward — The Position of the Merostomata. 295 



Plate behind 



the mouth 



(metastoma) . 



Plate-like and gill- 

 bearing appendages 

 of mid-body. 



Appendages 



of the 



fore-body 



(prosoma) . 



The enlarged 



basal joints 



act as jaws. 



- Median process borne by 

 plate No. 1, the genital 

 operculum, corresponding to 

 two segments of the upper 

 surface (supposed to dis- 

 tinguish the female). 



Segments of 

 hind-body with ^ 

 no appendages 



Post-anal tail-spine or telson. 



Fig. 2. Lower or ventral aspect of Eurypterus Fischeri, from the Upper 

 Silurian of Oesel in the Baltic. The drawing made from G. Holm's 

 original figure. Nat. size. Eeproduced by permission of the Trustees 

 of the British Museum (Natural History). 



