442 Proceedings of the Uoyal Physical Society. 



Dr Woodward thinks that the structure proves that E. 

 scabrosus had been an aquatic animal. Judging from the 

 fiorure which accompanies his paper, there seems to be no 

 organ displayed which would warrant this conjecture. The 

 appendage on the right side, marked 2 in the figure, is very 

 different from those succeeding it, and is in all probability, 

 as suggested by Professor Huxley,^ a portion of a chelate 

 limb. It is stouter than the others, and the second visible 

 joint bears a row of tubercles, which strongly recalls those 

 borne on the third joint of the chelate palpus in scorpions, 

 with which joint this is in all likelihood homologous. Dr 

 Woodward is therefore probably in the right in looking 

 upon it as one of the second pair of appendages. From the 

 study of the older Eurypterids, I am in a position to show 

 that Eurypterus scorpioides, Slimonia acuminata, as well as 

 Pterygotus Anglicus and P. lilohus, had each a pair of 

 chelate appendages, but these were the homologues of the 

 chelicerge, or the first pair of appendages in scorpions and 

 Limulus, and the phalangids and the falces of spiders. 

 Like the homologous organs in those animals, these bore no 

 gnathites at their bases, a fact long ago pointed out by 

 AVoodward in the case of the nippers of Pterygotus hilohios 

 and P. Anglicus.'^ 



In the above-mentioned older genera and species the 

 second pair of appendages was not chelate but antenniform, 

 as has been so well shown by Woodward with regard to 

 Slimonia and Eui^ypteriis scorpioides. Several specimens of 

 Pterygotus hilohus and one of P. Anglicus have come under 

 my notice, in which there are, besides the chelate appendage 

 and the large flattened so-called swimming paddle, four 

 other appendages on each side, the first of these being only 

 a little shorter than the other three, as in Euryptencs remijMS. 

 In recent spiders,phalangids,and Limuhis polyphemus this pair 

 is often peculiarly modified in the males for sexual purposes, 

 and it would appear that it is also the case in those of 



1 Ibid. See description of fig. 1, p. 484. 



2 Monograph of the British Fossil Crustacea belonging to the order Mero- 

 stomata. By Henry Woodward, LL.D,, etc. (Palseoutographical Society, 

 1886-1887, pp. 37 and 58.) 



