170 Proceedings of the Eoyal Physical Society. 



Genus Salteria — Wy. Thomson, 1864. 



(Mems. Geol. Survey, Decade xi., l^o. 6.) 



Salteria lyrimmva, Wy. Thomson. 



S. primmvcL — W. Thomson, loc. cit., pi. 6. 



Qls. — So far as I am aware little or nothing has been done 

 towards the elucidation of this peculiar trilobite since the 

 original description in 1864 Two of Mrs Gray's specimens 

 represent portions of the head, neither of which, strange to 

 say, afford any further details. Both, as in the original 

 specimens, are devoid of the free cheeks, but one of them 

 is larger than either of the latter. A third specimen exhibits 

 the body segments and pygidium in union, a feature which 

 is not represented in any of Professor Thomson's figures. 

 There are certainly seven body rings, and perhaps one or two 

 more, whilst on the central lobe of the pygidium ten divisions 

 are discernible. 



Loc. and Horizon. — Balcletchie, south-east of Girvan, in 

 rocks of Silurian age ; exact horizon uncertain. Sir Wyville 

 Thomson's specimens were found in "schists forming the 

 base of the Graptolite and Orthoceratite flags, Penwhapple 

 Glen, in the Girvan district — the equivalents of the Upper 

 Bala or Caradoc Eocks." 



Genus Acidaspis — Murchison, 1839. 



(Sil. Syst., p. 658.) 

 Acidasjois Graya^, sp. nov., Figs. 6-8. 

 Six Chars. — The head is not in a good state of preserva- 

 tion, and little can be said about the characters of the 

 glabella, its lobes and furrows, the facial suture, and the 

 flxed and movable cheeks, except that the glabella and lobes 

 appear to have been convex and prominent. The front 

 margins of the free cheeks are produced into a series of close 

 non-denticulated spines, which gradually decrease in length 

 forwards ; posterior angles produced into genal spines which 

 extend backwards for about half the length of the thorax, and 

 appear to be but little bent or curved ; neck segment promi- 

 nent and apparently non-spinous ; surface of the glabella and 

 lobes covered with scattered tubercles or granules. Thoracic 



