582 DR MALCOLM LAURIE ON 



margin — at least two of those being considerably larger than the rest. Of the last joint 

 almost nothing remains. Half a spine lying along the edge of the slab and a short 

 process arising at its base are all that are left. 



Appendage IV. — This limb (figs. 13 and 19) is somewhat longer and stouter than III. 

 Joint 3 is longer in proportion than in the foregoing appendage, and seems free from 

 spines. Joint 4 is the longest, and joint 5 the shortest in this leg, both being furnished 

 with well-developed spines. Joint 6 is long and tapering, and bears a remarkably 

 powerful spine at its distal extremity. The last joint is narrow and runs out into 

 three spines, that near the base being the stoutest. 



The 5th and 6th appendages have the elongated form characteristic of Stylonurus, 

 each joint being somewhat narrower than the last. The proximal joints of them are, 

 however, much wider and shorter in proportion than in St. ornatus. 



The points of difference between this form and St. ornatus are very marked. The 

 narrow carapace and wide metastoma would alone serve to distinguish the two forms, 

 while the greater length of the 3rd and 4th appendages, especially the 3rd, afford 

 equally good diagnostic characters. The proportion of the joints of the two posterior 

 limbs, and especially the shortness and width of the proximal joints, also offer a point 

 of difference. The only form I am acquainted with which resembles this species in the 

 form of the carapace is St. excelsior (3) from the Upper Devonian (Catskill group) of 

 New York. The appendages of this form do not, unfortunately, admit of comparison 

 with those of St. elegans. 



Drepanopterus. 



Two new species come under this genus, and the point of chief generic importance 

 in the light of these new forms would seem to be a negative one : — " Last pair of 

 appendages neither expanded, as in Eurypterus, etc., nor excessively elongated, as in 

 Stylonwus." 



The genus unquestionably comes very near Stylonurus in some respects. The form 

 of the carapace and the comparatively elongated last appendages in D. Pentlandicus are 

 suggestive of stylonuroid affinities, but D. bembicoides is a very well marked form, 

 easily separated from Stylonurus, and quite justifies the existence of the genus. 



Drepanopterus lobatus, n. sp. (PI. II., fig. 16. PI. III., figs. 17, 18.) 



Carapace almost semi-circular ; body without marked differentiation of meso- and 

 metasoma ; last segment with posterior angles produced into ovate lobes ; telson long. 



I have ventured to found this species for the reception of three or four specimens, 

 which are most definitely characterised by the form of the last segment. 



The carapace (PI. II., fig. 16) has a length of 15 mm. and a breadth at its widest 

 point of 25 mm. The proportion in this specimen is probably not quite correct, as the 



