EURYPTERID REMAINS FROM THE PENTLAND HILLS. 



583 



animal seems to have been squeezed out laterally and slightly telescoped into itself. 

 The greatest width of the carapace is about one-third from the posterior margin. The 

 position of the eyes is unfortunately not shown. 



The body segments become progressively narrower and longer from before back- 

 wards. The last six at least have the posterior angles produced into processes. These 

 are large on the 11th segment, and on the 12th form a pair of ovate lobes about the 

 same length as the segment itself. The telson is long, and in one specimen (PI. III., 

 fig. 17) curved, but this is probably accidental. The end of the telson is not shown. 



Some fragments of a carapace and body segments with the two last limbs attached 

 (PL III., fig. 18), I am inclined for the present to regard as belonging to this species, 

 and it is this specimen which has decided the generic position of the species. Apart 

 from the limbs here shown, the general body shape of D. lobatus is more suggestive of 

 a Stylonurus. The carapace shows little of the shape, but is covered with a scattered 

 punctate marking. The body segments, portions of six of which are shown, are covered 

 — especially the anterior part of each segment, with flattened scale markings. The 

 greater part of appendages V. and VI. is shown, and these undoubtedly belong to a 

 Drepanopterus though approaching the Stylonurus form more closely than D, bemby- 

 coides. The fifth appendage appears to have had a long spine arising from probably 

 the 5th segment. The sixth appendage has the second and third joints considerably 

 elongated, while the fourth, fifth, sixth, and seventh joints might belong to D. bembi- 

 coides. The measurements of the limbs are : — 







Appendage 



V. 



Appendage VI. 



Segment. 





Length. 



Breadth. 



Length. Breadth 



3 





1 



9 mm. 



19 mm. 6 mm. 



4 





12 mm. 



6 mm. 



7 mm. 6 mm. 



5 

 6 



} 



16 mm. 



I 4 - 5 mm. 

 ( 2 mm. 



9 mm. 5 mm. 

 6 mm. 3 mm. 



7 





5 mm. 



l - 2 mm. 



6 mm. 2 mm. 



This specimen, whether belonging to D. lobatus or not, is interesting as giving us 

 an intermediate form between D. bembicoides and Stylonurus. 



Drepanopterus bembycoides, n. sp. (PI. III., figs. 20-21). 



Surface smooth ; carapace with comparatively straight anterior margin and sides, 

 length = one-half breadth ; body tapering regularly and ending in a stout conical tail 

 spine ; segments increasing in length towards posterior end ; eyes inside a well-marked 

 marginal band ; limbs increasing in length from before backwards, last pair neither 

 expanded as in Eurypterus nor elongated as in Stylonurus, ending in a slightly sickle- 

 shaped subconical joint ; spines wanting on the limbs ; metastoma oval ; genital plate 

 with broad oval median process hardly extending beyond lateral portions. 



The carapace, which, as stated above, is twice as broad as it is long, has a well-marked 

 border about 5 mm. wide. This border is ornamented with fine reticulating lines. 



VOL. XXXIX. PART III. (NO. 19). 4 T 



