576 DR MALCOLM LAURIE ON 



forms in this particular bed along with masses of " Dictyocaris " and layers of structure- 

 less black matter must remain obscure. They must have existed both before and after 

 the period marked by this particular bed, but so far as is known have with one excep- 

 tion left no trace in the surrounding rocks. The variety of forms — 4 genera being 

 represented — suggest that even in this bed we are far from the time when this group 

 came into existence. On the other hand, no one, I think, will deny that Drepanopterus 

 hrmbicoides is the least differentiated form known. The presence of a Scorpion indi- 

 cates that the origin of that group is earlier than had been supposed, a conclusion which 

 agrees quite well with the views I have published elsewhere as to the relation of the 

 Scorpions and Eurypterids. That this Scorpion was an air-breather does not necessarily 

 follow. The characters which mark it as a Scorpion may well have been developed 

 before the terrestrial mode of life and consequent modification of the respiratory organs 

 took place. Unfortunately, these respiratory organs are necessarily so delicate in tex- 

 ture that we know very little of their structure and arrangement in any of the fossil 

 orthropoda, and, as in respect of many other interesting points in Palaeontology, must 

 wait for further evidence before we can pronounce an opinion. 



I cannot let this opportunity pass without expressing the gratitude I owe to Dr 

 Traquair for the opportunity of examining the Hardie Collection, and for the sympathy 

 and encouragement which has helped me to surmount many difficulties. I am also in- 

 debted to Mr B. N. Peach for much assistance in the more difficult points which have 

 arisen ; assistance which only those who have worked with him can appreciate the 

 value of. 



The forms to be described come under six genera : — Palceophonus, Slimonia, 

 Stylonurus, DrepanopAerus, Eurypterus, and Bembicosoma (n. g.), and are dealt with 

 in the above order. The new species are Palceophonus loudonensis, Slimonia dubia, 

 Stylonurus elegans, Drepanopterus lobatus, Drepanopterus bembicoides, Eurypterus 

 scoticus, E. minor, and Bembicosoma pomphicus. 



Palceophonus loudonensis, n. sp. (PI. I., fig. 1.) 



Carapace long and narrow, median eyes on a double papilla verjr far forward ; 

 mesosomatic sclerites band-like ; tail long ; chelicerse comparatively long and narrow. 



The single specimen on which this species is founded is very obscure — so much so 

 that it was long before I realised that it was anything more than a crushed Eurypterus. ! 

 It had also been carelessly developed, so that the limbs for the most part are destroyed, 

 and the tail entirely loses itself among some of the black layers which are so frequent 

 in this Gutterford bed. The specimen shows the dorsal surface. 



The carapace is 10 mm. long and 7 mm. wide, a very different proportion to 

 Palceophonus nuncius (9), in which the carapace is 7 '5 mm. long and 8 mm. 

 wide. The anterior margin is distinctly concave, and the sides almost parallel, but 

 slightly convex. The posterior margin appears fairly straight. Situated about 1 mm. 



