PART III. 

 DITHYROCARIS. 



I. INTRODUCTORY REMARKS. 



It will be seen in our list of synonyms at pp. 129, 130 that the genus Dithyro- 

 caris, first known and named as Argas in 1835, and frequently mentioned by 

 geologists subsequently, has had its features and structure described chiefly by 

 J. Scouler, J. B. Portlock, F. M'Coy, H. Woodward, R. Etheridge, jun., James 

 Hall, and J. M. Clarke ; whilst F. A. Romer, Ludwig, Meek and Worthen, and 

 Scudder have noticed some fragmentary portions, chiefly of the caudal extremity. 



So many of the known remains of this genus have been found in the Carboni- 

 ferous strata of the West of Scotland that it is advisable to have before us, for 

 easy reference, a classified list of the localities there, and the geological horizons, 

 from which the specimens have been obtained. The following list of the local 

 formations and the species found in them has been made with the help of Dr. John 

 Young, F.G.S., of the Hunterian Museum, Glasgow. 



A List of the Species of Dithyrocaris and allied genera, with their Localities in 

 the Carboniferous Formations of Scotland and elsewhere. 



In the Upper Limestone series : 



Ghoenocaris tenuistriata (M'Coy). Settle, Yorkshire; also Belgium. 



— Youngii, sp. nov. Lingula-shale, Robroystone, near Glasgow. 

 Dithyrocaris testudinea, Scouler. Cement-Limestone, Orchard, Glasgow. 



In the Middle Coal and Limestone series : 



Dithyrocaris tricomis, Scouler. ) Ironstone pits, Inkermann, near 



— testudinea, Scouler. ) Paisley. 



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