22 CARBONIFEROUS LAMELLIBRANCHIATA. 



An enlarged view of these specimens is also given, to show the finely ornamented 

 surface. The series from Potmetal Plantation show us casts of the interior, but 

 the characteristic external markings are seen as hollow casts of the exterior. 



The specimen in the Griffith Collection, now labelled as Lanistes obtusiis, has 

 apparently no connection with the figure, and belongs to quite another genus of 

 shells. 



Leiopteria divisa, M'Coi/, sp., 1844. Vol. I, Plate XIII, figs. 11 — 14. 



Vide Parallelodon divisus, Hind, 1897. Mou. Brit. Carb. Lamell., vol. i, p. 172, 



pi. xiii, figs. 11 — 14. 



Observations. — Further research has convinced me that my reference of this 

 shell to Parallelodon was a mistake ; the reference was made on account of the 

 hinge characters. Further examination shows that the hinge is really not that of 

 the Parallelodon type, but belongs to Leiopteria, and the shape and ornament of the 

 shell are characteristic of this genus. One peculiarity is present, and that is the 

 narrow oblique trench in the anterior part of the shell, which gives the name to the 

 species, and which takes the place of the oblique compression always present in this 

 situation in other members of the genus. An examination of a number of specimens 

 seems to indicate that this groove is not always so well marked, and specimens 

 occur, which do not appear to have suffered from crushing, in which hardly a trace 

 of the trench can be seen. Tlie object of this groove is not apparent. 



Genus Actinopteria, Eall^ 1884. 



Pteeonites, M'Coy (pars), 1844. Synops. Oarb. Foss. Ireland, p. 81. 

 Actinopteria, Hall, 1884. Pal. N. York, vol. v, pt. 1, Lamell., p. xii. 



Generic Characters. — Shell more or less oblique, subquadrate. Anterior end 

 very short, posterior end expanded and compressed, with a sinuous outline and a 

 hollowed dorsal slope. Hinge-line straight. Umbones placed very far forwards, 

 subterminal. 



Interior. — Hinge-line edentulous (Hall). 



E.vferior. — The surface is marked with fine, not very conspicuous, concentric 

 lines of growth, and ornamented with well-marked, close, radiating ribs. 

 Shell thin. 



Ohservations. — Hall defines his genus Actinopteria as follows : — " Characterised 



