UPPER SILURIAN ROCKS OP THE PENTLAND HILLS. 



157 



Eurypterus conicus, n. sp. (PL II. figs. 12, 13 ; PL III. fig. 14.) 



This species is represented by a number of more or less complete specimens, the 

 largest of which is about 150 mm. in length. 



The carapace is semicircular, but differs a good deal in different specimens owing to 

 distortion. Fig. 14 is probably nearest to the original shape, and in this specimen it 

 measures 28 mm. in breadth and 19 mm. in length. 



The dorsal surface is not seen, but the position of the eyes can be distinctly made 

 out. They are large, 8 mm. in length, and somewhat oval in form, and about equidistant 

 from the anterior and posterior margins of the carapace. The anterior ends of the eyes 

 approach very close to the side of the carapace (1*5 mm.), but the posterior ends are 

 slightly more distant. 



The metastoma is not seen, but the bases of the feet are very well shown. The last 

 pair (" ectognaths ,T ) are broad and angular, the external angle being truncated parallel 

 to the axis of the body for the attachment of the limb. The bases of four other pairs of 

 postoral appendages can be made out, and also the position of the small and as yet 

 undescribed chelicerse (fig. 14). 



The body in fig. 14, which I take to be the more normal form, the other being drawn 

 out, tapers regularly from its point of attachment to the carapace to the telson, and the 

 segments increase slightly in length. In fig. 12 the body is longer and narrower. The 

 detailed measurements of both are as follows : — 



Fig. 14. 



Fig. 12. 



Segment. 



1. 



2. 



3. 



4. 



5. 



6. 



7. 



8. 



9. 

 10. 

 11. 

 12. 

 Telson, 



Len 



gth. 



Width. 



}« 





28 



mm 



mm. 



28 



» 



4-5 



» 



27 



» 



4 



j» 



25 



» 



4 



» 



24 



>i 



4 



» 



23 



» 



4-5 



n 



21 



;> 



6-5 



3) 



19 



» 



5 



yy 



16 



yy 



55 



*> 



14 



J* 



7 



» 



12 



9r 



7 



„ 



9 



it 



28 



?» 



5 



)> 



Length. 



Width. 



2-5 



mm. 



21 mm 



25 



» 



22 „ 



4 



?? 



22 „ 



4 



)> 



21 „ 



5 



j? 



20 „ 



5 



19 



19 „ 



4-5 



» 



17 „ 



7 



>> 



15 „ 



7 



)J 



? 



8 



J) 



12 „ 



8 



» 



10 „ 



11 



?) 



7-5 „ 



30 



>> 



5 „ 



Length of body, including carapace and telson — fig. 14, 105 mm. ; fig. 12, 121 mm. 

 The posterior angles of the segments project slightly here and there, but there is no 

 sign of regular epimera. 



The telson tapers regularly to a fine point. 



The genital plate is seen in fig. 12. The lateral plates are a good deal narrower than 



