160 



MR MALCOLM LAURIE ON SOME EURYPTERID REMAINS FROM THE 



of each of the first six segments is a comparatively large protuberance, somewhat 

 elongated transversely, and the whole surface of the segments appears to have been 

 closely covered with a minute, peculiar, and rather irregular marking, which, however, is 

 only preserved in parts. 



The four distal joints of a limb (probably the last), measuring 94 mm. in length, are 

 well shown, and differ from anything hitherto described among the Merostomata. The 

 first three of these joints differ chiefly from each other in length. The first is ,33 mm. 

 long, tapering, and slightly hourglass-shaped, the breadth at the proximal end being 

 11 mm., in the middle 9 mm., and' at the distal extremity 10 mm. The second joint is 

 27 mm. long, rather more tapering, and slightly concave on the posterior side. The 

 third joint was much shorter (16 mm.), but is too much broken to allow its shape to be 

 well made out. The last joint is 23 mm. long, and falcate in shape. The posterior 

 margin is concave and evenly curved throughout its length, while the anterior margin 

 runs for a short distance (5 mm.) approximately parallel to the posterior, and then curves 

 strongly forward and sweeps round to meet the posterior margin at the pointed termi- 

 nation of the limb. The breadth of this joint at its articulation with the preceding one 

 is 7*3 mm., and at its broadest, which is 15 mm. along it, it measures 11 mm. 



The surface of the limb is covered with a punctate rather than scale-like marking. 

 The marks are of two distinct sizes, the larger ones being distributed evenly at some 

 little distance from each other, the space between them being occupied by the smaller 

 ones. 



Traces of another limb, which must have equalled this one in breadth, are seen 

 immediately in front of it at the side of the carapace, but they are too indistinct to 

 admit of description. 



A small specimen (fig. 17) showing portions of the 3rd to 8th segments, with the 

 whole of the 9th to 12th, and the telson, appears from the markings to belong to this 

 species. The body in this specimen tapers rapidly to the 9th segment, and then more 

 gradually to the 12th, the last four segments increasing in length as they diminish in 

 width. The size of the segments, so far as it could be ascertained, is as follows : — 



3rd segment. 



4th 



5th 



6th 



7 th 



8th 



9th 

 10th 

 11th 

 12th 

 Telson 



3 ? 



mm. 



3 



)> 



25 



33 



'2 



» 



? 



» 



3 



» 



3 



J) 



4 



5) 



5-5 



>> 



17 



» 



? mm. wide. 



? 



? 



? 



? 



9 



8 



7 



5 



3 



The 12th segment is a truncated cone, narrowing from 5*5 mm. to 4'5 mm. 



