102 PROCEEDINGS OF THE 



figures. The apex is also more prominent and a little abruptly 

 truncated behind. The surface of the exposed region is very 

 pustulose, and the posterior inserted margin strongly radiately 

 ridged. On the whole, the form of this plate is that of C. 

 Youngianus, while the minute details are quite those of that before 

 referred to as C. subquadrahis, except, of course, that one is an inter- 

 mediate and the other a posterior plate. If the present specimen 

 is truly C. Youngiamcs, I think it not at all unlikely that it and 0. 

 subquadratus are plates of one and the same form ; all the charac- 

 ters point in this direction. 



One of de Ryckholt's figures* of Cliitonelhis cordifer, de Koninck 

 bears much likeness to the posterior plate of C. Youngianus. 



Locality and Horizon. — Cunningham Baidland, near Dairy ; 

 Lower Carboniferous Limestone group. 



Collection. — J. Armstrong. 



3. LIST OF WORKS AND PAPERS REFERRING TO THE PALAEOZOIC 



CHITONIDAE. 



1. Miinster, G. Graf zu. — Beitrage zur Petrefacten-kunde. 4to, 

 Beyreuth, {Chiton priscus, Miinster. Heft i., 1843, p. 60.) 



2. De Koninck^ L. G. — Description des Animaux Foss., Terrain 

 Carbonifere de Belgique, 4to, Liege, 1842-44. (Genus Chiton, 

 p. 319.) 



3. Ryclxholt, Baron de. — Resume" geologique sur le genre Chiton, 

 Lin. Bidl. de V Acad. R. de Bruxelles, 1845, xii., pt. 2, pp. 36-62, 

 pis., 1-4. 



4. RycJxh olt, Baron de. —Melanges Paleontologiques; Genus Chiton, 

 pp. 63-65, 4to. (Extrait de tome xxiv. des Mem. de VAcad. R. de 

 Belgique, p. 63.) 



5. Salter, J. W. — Description of a Fossil Chiton from the 

 Silurian Rocks, with Remarks on the Fossil Species of the Genus. 

 Quart. Jour. Geol. Soc, 1847, iii., pp. 48-52. 



6. Roeiuer, F. A. — Beitrage zur Geologischen Kenntniss des 

 nordwestlichen Harzgebirges. Palaeontographica, 1855, v., lief. 1, 

 pp. 1-46. (Chiton laevigatas, F.A.R., p. 36.) 



7. Sandberger, Drs. G. § F. — Die Versteinerungen des Rheinis- 

 chen Schichtensy stems in Nassau, 4to, 1850-56. (Genus fihiton, 

 pp. 237-240.) 



8. Kirkby, J. W. — On some Permian Fossils from Durham. 



* Loc. cit., t. 4, f. 15. 



