EURYPTERID REMAINS FROM THE PENTLAND HILLS. 579 



shape of the body differs from S. acuminata in tapering evenly the whole way down, 

 instead of narrowing suddenly at the seventh segment into a cylindrical tail. This 

 difference of body form is so marked that at first I was disposed to place these body 

 segments and telson under Pterygotus, to which Slimonia is closely allied. Slimonia 

 acuminata comes from the Lesmahagow beds, and belongs to a higher horizon than the 

 Pentland beds. A telson indistinguishable from S. acuminata has also been found in 

 the Pentlands in beds belonging to a higher horizon in the Esk Valley. 



Stylonurus. 

 Stylonurus macrophthalmus. (PL I., figs. 4-7.) 



Of this form the general shape is better shown in fig. 4 than in the type specimens 

 described in my former paper. The median appendage of the genital operculum is 

 characterised by extreme length, reaching down across four segments. It appears to 

 have terminated in a point. The hind segments of the body are very characteristically 

 furnished with epimera (figs. 5-6). These are not mere backward prolongations of the 

 posterior angles of the segments, but project from the sides of each segment, being 

 attached by a narrower peduncle, and expanding into a thin oval plate. The only 

 form with epimera approaching these is St. scoticus, but in it they are not so well 

 marked or so large in proportion. 



Appendage III. (fig. 4) is moderately long and very stout, ending in a curved spine. 

 The other joints probably bore spines also, as in St. ornatus (7). 



Appendage IV. (fig. 7) is about twice the length of III., but not so broad. The 

 distal joints are furnished with strong, curved spines — probably a pair to each segment, 

 and the limb terminates in a spine. 



Appendages V. and VI. do not differ much from the typical Stylonurus form. 

 V. seems to have a small spine arising from the anterior side of the joint, between 

 segments 4 and 5, while VI. shows the narrowing and elongation characteristic of 

 Stylonurus to a marked degree. 



Stylonurus ornatus. (PI. I., fig. 8. PI. II., figs. 10-12.) 



A great deal has been added to our knowledge of this species. Only the general 

 body form the metastoma, and portions of the last appendage and telson were described 

 in my former paper. The greater part of the structure of all the six appendages has 

 now been made out and the telson completed. In many specimens, the characteristic 

 ornamentation is quite invisible, but I regard this as merely due to difference in the 

 details of preservation. 



Appendage I. (PI. I., fig. 8). — The most anterior appendages are a small pair of 

 chelicerse well shown in the figure. Only the two end joints forming the pincers are pre- 

 served, and the bases of the first somewhat broken. The proximal joint, probably the 

 2nd of the limb, is 10 mm. long, with an articular surface for the terminal joint half way 



