

518 MR MALCOLM LAURIE ON THE 



genera are, the position of the eyes, which are placed on the dorsal surface of the cara- 

 pace, and the long spine-like telson. The appendages are much the same in general form 

 as those of Pterygotus, but have certain well marked points of difference. The last pair 

 have their proximal joints narrower and more cylindrical, while the last two joints are 

 proportionally more expanded in the majority of cases. Of the four pairs of walking 

 legs, the first three resemble one another closely, being simple, somewhat short sub-cylin- 

 drical limbs, bearing spines on the last four joints. The fourth pair differ from the others 

 in being considerably longer and having no spines except at the end of the limb, which 

 terminates in three spines. This differentiation of the fourth walking leg (fifth appen- 

 dage) seems characteristic of the genus, and constitutes a step towards such forms as 

 Stylonurus. 



The first pair of appendages has in this genus, as in Slimonia, long remained obscure. 

 Hall* says, "In two instances I have seen some indication of a small appendage in this 

 position, but a further examination does not offer any confirmation of this view." 

 Schmidt t was the first to describe it as actually existing, and he makes it out as a pair of 

 jointed filiform appendages lying between the basis of the first pair of walking legs. He 

 has apparently only found them in one specimen, but judging from his figure 

 (pi. iii. fig. la) they seem clearly enough shown. Not having seen the specimen in 

 question, I am unable to offer any criticism on his interpretation of this structure, but if 

 he is correct in his description it differs very markedly from anything I have been able to 

 find in other specimens. The first example of what I believe to be the preoral appendages 

 was pointed out to me by Mr B. N. Peach, and is the specimen of Eurypterus scorpioides 

 figured in Dr Woodward's monograph (pi. xxx. fig. 9), and now in the Geological 

 Museum, Jermyn Street, — not, as stated in the explanation of the plate, in the British 

 Museum. In the figure, and more clearly in the original specimen, may be seen what 

 appear to me a pair of small chelate structures, lying with their apices close behind the 

 front margin of the metastoma. The one on the right-hand side of the middle line is 

 most distinct, and measures 17 mm. in length, the pincers occupying 10 mm. of this. 

 The only other specimen in which I have been fortunate enough to see these appendages 

 is the specimen of E. conicus which I have figured (pi. iii. fig. 14) in my paper on " Some 

 Eurypterids from the Pentlands."J In this specimen the bases of the five pairs of limbs 

 can be made out, and lying between the most anterior pair is a pair of conical depressions, 

 the apices of the cones being directed backward. These structures, which measure some 

 3 mm. in length, are not sufficiently well preserved for one to say definitely that they 

 are chelate, but their general form, taken together with the structures described above 

 in E. scorpioides, and the presence of chelate preoral appendages in both Pterygotus and 

 Slimonia, justify one, I think, in assuming that such was the case. 



If my interpretation of these structures is correct, it would seem to be necessary to 

 separate E. Fischeri from E. scorpioides and E. conicus as at least a distinct genus. 



* Loc. cit., p. 30G, footnote. t hoc. cit., pi. iii. figs. 1 and la. 



X Trans, lio;/. Soc. EdiiL,, vol. xxxvi. 



