584 DR MALCOLM LAURIE ON 



Immediately inside the border and just behind the antero-lateral angle of the carapace 

 are the comparatively small oval eyes. The metastoma (PI. III., fig. 20) is oval, narrow- 

 ing slightly towards the front, and with a small but deeply-cut notch in the anterior 

 border. 



The limbs are short and stout, formed of a series of sub-cylindrical joints of approxi- 

 mately the same length. Each joint is narrower than the one before it, and the distal 

 end of each expands slightly. The last joint is subconical and slightly concave on the 

 post. marg. 



No spines have been observed on any of the appendages. The most marked feature 

 of these limbs is the close resemblance of one to another and the absence of any marked 

 specialisation. The increase in size from before backwards is an increase in both length 

 and breadth, so that the proportions of the limbs remain unaltered. 



The body segments are short, increasing slightly in length towards the posterior end 

 as far as the 11th. The 12th is very much longer than any of the preceding ones, and 

 has the shape of a truncated cone, from the posterior end of which arises the short conical 

 telson. The tapering of the body is almost uniform from the hind margin of the cara- 

 pace to the end of the telson. The tergites of the segments have their posterior angles 

 produced into short spines. 



The genital plate is short and the median process oval and scarcely projecting beyond 

 the posterior margin of the plate. 



This form is easily distinguished from D. pentlandicus by the smooth body surface, 

 the less central position of the eyes, the markedly conical form of the body. The pro- 

 portions of the carapace and indeed of the whole animal show a greater breadth in propor- 

 tion to the length. It resembles E. conicus in general form, but is usually easily dis- 

 tinguished by the large submarginal eyes of conicus and the absence in it of the well- 

 marked border to the carapace. The telson in Conicus is also much longer and slighter. 



Taken as a whole, this form appears to me the most primitive Eurypterid known. 

 The absence of differentiation of the body into meso- and metasomatic regions is shared 

 by it with several Eurypterus forms, but to this must be added the comparatively slight 

 development of the genital plate, and above all the legs. The almost entire absence 

 (much more marked than in D. pentlandicus) of differentiation of the posterior pair, either 

 as flattened paddles as in the majority of the Eurypterids, or as enormously elongated 

 walking legs as in Stylonurus, is a very striking feature. It is unfortunate that in tins 

 as in so many of these Pentland specimens, the form of the gnathobases cannot be made 

 out. 



I have termed it bembycoides from /3e/u,/3<,£, a peg-top. 



Drepanopterus pentlandicus. (PI. IV., fig. 22.) 



Some good specimens of this species have come to light. The most instructive isj 

 the small individual figured in fig. 22. It is less distorted than the type specimen, audi 



