BUFFALO SOCIETY OF NATURAL SCIENCES 241 



first three pairs of legs relatively short and stout, with only two 

 short, curved spines on each segment, as in Drepanopterus and 

 Eurypterus. 



From the Wenlock, Laurie has also described three species of 

 Eurypterus : E. conicus, E. minor and E. cyclophthalmus. These are 

 three small species which are not very well represented and which 

 are primitive or retarded in development. They are not related to 

 any American forms nor do they appear to fill ancestral positions, for 

 the British species of the Upper Siluric and Devonic. In some one 

 characteristic a Wenlock species seems to foreshadow a later one, 

 but phyletic fines are difficult, if not impossible, to trace. The exceed- 

 ingly large eyes in the single known specimen of E. cyclophthalmus, 

 and in E. conicus, and the small size as well as the general form 

 suggest that these two species are larval forms. Clarke and Ruede- 

 mann consider that E. minor also is either immature or has had its 

 development arrested. They think that such is especially the case 

 in Bembicosoma pomphicus Laurie, a small, stunted form with large 

 head, rapidly tapering body, and " warty texture of skin." 



The genus Drepanopterus Laurie is now placed by Clarke and 

 Ruedemann as a subgenus of Stylonurus. To this group belong 

 Laurie's three species: D. bembicoides, D. lobatus, and D. pentlandicus , 

 which need not be discussed in detail since they show no affinities 

 either to American or to continental European forms. The species 

 described by Laurie as Eurypterus scoticus has since been revised by 

 Clarke and Ruedemann who recognized its affinities to Eusarcus. 

 In the American faunas it finds its nearest representative in E. scor- 

 pionis from the Bertie. Because of the impossibility of making 

 accurate measurements of the proportions of different parts of the 

 bodies and of obtaining exact outlines to show the form, one is unable* 

 to make careful comparisons. 



The only remaining species in the Wenlock eurypterid fauna is 

 Slimonia dubia Laurie, a small individual, much broken and without 

 appendages. Laurie has included in this species a second individual 

 which shows a portion of the telson. Since the genus at present 

 comprises only two species, the one just mentioned, and S. acuminata 

 from the Ludlow, there is no opportunity to trace relationships over 

 broad areas. The main reasons for making a new species of the 

 Wenlock Slimonia, were, the difference in geologic age between the 

 two forms, and the fact that the Pentland Hills individual was gradu- 

 ally tapering instead of abruptly contracted in the seventh segment 

 into a telson. 



