'Woodward and Etheridge — On Dithyrocarls. 107 



pendent for convenient supply of fuel. In bringing the present 

 paper to a close, the writer feels that he would but inadequately 

 perform his task if he confined himself to the discussion of seams of 

 •coal, without reference to the men by whose labour they are made 

 available, or without expressing a hope that with increased industrial 

 enterprise, there may be henceforth coupled in this district a reason- 

 able solicitude for the material comfort of the working miner. 



In conclusion, the writer offers his best thanks to the several 

 mining proprietors for aiding him in his inquiries, and enabling him 

 to give, with accuracy, the condition of the field as regards its 

 present output of coal. 



II. — On some Specimens of Bithyrocabis from the Carbonifebous 

 Limestone series, East Kilbride, and from the Old Eed 

 Sandstone of Lanarkshire. 



By Henry Woodward, F.R.S., F.G.S., etc., 

 of the British Museum, and 



EoBERT Etheridge, Jun., F.G.S., etc., 

 of the Geological Survey of Scotland. 



(PLATE V.) 



{Continued from Novemher, 1873, p. 486.) 



3. BiTHTRocARis ovALis, W. and E. (PI. V. Fig. 1), Mems. Geol. 

 Survey, Expl. Sheet 23, Spotland, 1873, p. 100. 



This species most nearly resembles D. Colei ^ in outline, but is 

 little more than half its size, and is quite destitute of the strong 

 median and lateral ridges which mark Portlock's species. 



The specimen is from East Kilbride, and was obtained by Mr. A. 

 Paton ; it has both the valves united, although somewhat fractured 

 and imperfect. 



Its general outline is oval ; its length as contrasted with its breadth 

 being as three to two. 



The anterior ends of the conjoined valves are roundly produced, 

 inclosing a slight mesial indentation in front. 



The posterior border of the shield is more deeply indented in the 

 centre, and the lateral margins are produced and terminate in an 

 acute spine on each side. 



The greatest length of the shield, measured along the latero-mesial 

 line, to the tip of the posterior spine, is 55 mm. ; its length along the 

 dorsal line is 45 mm. Its greatest breadth across both valves is 

 38 mm. 



The surface of the carapace is nearly smooth, save at the anterior 

 extremity and close to each side of the mesial line, where it is finely 

 granulated ; the maxillary ridges are situated about 4 mm. on either 

 side of the mesial line, which is not very strongly marked ; the two 

 lateral ridges running parallel to the mesial ridge are only faintly 

 indicated. 



The margins of the shield are decorticated, but the impression of 

 the double border is clearly seen upon the matrix. 



1 See Geological Report on Londonderry, etc., by Captain Portlock, Dublin, 1843, 

 p. 314, pi. xii. 



