EURYPTERID REMAINS FROM THE PENTLAND HILLS. 581 



specimen (PI. II. , fig. 13) shows about half the carapace, the metastoma, fragments 

 of five body segments, and portions of appendages III. to VI. of the left side. Another 

 specimen (PL III., fig. 19), mounted in the same slab of plaster of paris, shows append- 

 ages III., IV., V., and VI., and is probably the other side of the same animal as fig. 13, 

 a portion of the carapace being gone. Two other specimens (one the very fragmentary 

 reverse of the other) show parts of the carapace, and appendages III.-VI. of a much 

 smaller individual. These two specimens have been useful in confirming certain points, 

 but have added nothing to the information derived from the specimens, figured. The 

 other two specimens show the posterior body segments, and I have ascribed them to 

 this species, as they show certain differences from the corresponding portions of St. 

 ornatus. Their place must be considered as only probable, however, till the discovery 

 of fresh material. A somewhat broken carapace (fig. 14) belonging to a small indi- 

 vidual is valuable as giving the anterior margin and the position of the eyes. 



The carapace (PI. II., fig. 13) is widest about one-third from the hind margin. In 

 front of this it narrows, the anterior one-third being concave in outline. There is a 

 narrow but well-marked border in the anterior third which narrows as it approaches the 

 level of Appendage IV. Whether it continues beyond that point is doubtful, the outline 

 of the carapace being rather indicated than preserved behind this point. The anterior 

 margin (fig. 14) is crenulated. 



The metastoma is proportionately broad and short and slightly concave on its 

 anterior and posterior margins. The ratio of width to length is 5 to 7, a marked con- 

 trast to St. ornatus in which the ratio is 5 to 11. The proportionate width of meta- 

 stoma and carapace also differs markedly from St. ornatus, being in St. elegans as 5 to 

 11*5, and in St. ornatus as 1 to 8. The surface of the metastoma was covered with 

 scattered projections. 



The only appendages known are parts of III., IV., V., and VI., lying beyond, the 

 carapace. The gnathobases have left no impressions. 



The third and fourth appendages are well furnished with spines along the posterior 

 margin of the four distal joints. These spines are slightly curved and longitudinally 

 striated and were probably arranged in a double row. Those towards the end of the 

 limb are larger than those towards the base. 



Appendage III. — Presuming that this appendage consisted of the typical number of 

 joints (i.e. 7), portions of 3 and 4 are shown on the left side (fig. 13), and 3, 4, 5, 6, and 

 probably the beginning of 7, on the right side along with a small fraction of 2 (fig. 19). 

 Joint 3 is short, the length being only one-third greater than the width. There are appar- 

 ently no spines on the posterior margin, but the distal end of the anterior margin is pro- 

 duced into a short spine (fig. 13). Joint 4 is twice the length of joint 3, and appears to 

 expand at the distal end owing to the presence of spines on both anterior and posterior 

 margins. The posterior margin bears a number of spines. Joint 5 tapers slightly and 

 is three-fourths the length of joint 4. It is furnished with spines on the posterior surface. 

 Joint 6 is nearly the same length and is well furnished with spines along the posterior 



