270 



The Family Idoteidcc are thus characterised " Terminal appendages of the 

 last false legs very large, lamellated, covering all the lower surface of the 

 ahdomen, and not projecting beyond the first segment which is shield-like and 

 very large." 



In Arcturus the body is long, the four first pairs of legs are lamellar at the 

 end, and not fitted for walking or seizing ; the three last pairs of legs are formed 

 for walking. The Antenna are very large, and are (like the legs of other genera) 

 employed in seizing and enclosing their prey. 



In Arcturus Bafiini the segments are not very rugose, but each is marked 

 by two very prominent spines situated in the same position as the depression in 

 the fossil tergum (sketch No. 9, fig. 1A). 



In A. longicornis, Sby., another and smaller species found on our own 

 shores, the dorsal aspect of the body is rugose, in the same irregular manner as 

 in the fossil. 



Comparing the fossil with the recent Crustacean, it is probable the segments in 

 Sketch No. 9 formed two of the three posterior appendages furnished with 

 walking limbs. 



It would be rash to speculate upon the actual relation of the other 

 fragments (sketch No. 10), but they are clearly parts of both simple (fig. 1) and 

 chelate (figs. 2 and 3) appendages. Perhaps fig. 1 (sketch 10) may have been one 

 or more of the antennas crushed, which were probably of large size in the fossil as 

 well as in the recent form. 



I propose to name this fossil Prcearcturus gigas, although I hope, through 

 the activity of the members of the Woolhope Club, to have ere long to re- 

 describe it from more perfect remains. 



