APPENDIX. 341 



convex, and marked by concentric lines of growth. The internal characters agree 

 pretty closely with those described in 0. sagittalis. 



Position and Locality. The Lower Tremadoc beds, Craig-y-dinas, North Wales. 



Obolella maculata, Hicks. PI. L, figs. 18 — 21. 



Obolella maculata, Hicks, MS. Report Brit. Assoc, for 1865, p. 285, 1866. 

 — — Bav. Geol. Mag., vol. v, p. 311, pi. xvi, figs. 1—3, 1868. 



Spec. Char. Shell small, transversely oval; valves moderately convex; four lines in 

 length, by five in breadth. Beak very obtusely acuminated ; front broadly rounded ; 

 greatest breadth at about the middle of the shell ; surface smooth, marked only by fine 

 concentric lines of growth. Interior incompletely known. 



Obs. It has unfortunately not been possible to offer a description of the internal 

 characters of this interesting fossil. I have, however, attempted to draw what little Avas 

 clearly observable in its interior, 0. maculata difiers considerably from 0. sagittalis on 

 account of its much larger dimensions and very transverse shape. The shell appears also 

 to have been much thinner than that of the species last mentioned, and is often found 

 very much flattened in the rock in which it is imbedded. 



Position and Locality. Obolella maculata was found by Mr. Hicks chiefly in the 

 middle portion of the ' Msenevian Group' at Porth-y-rhaw, St. David's. Mr. Belt ob- 

 tained it from the " Lower Msenevian," at Camlan ; also in the lower portion of the group 

 at Gwynfynydd, North Wales. 



Genus — Obolus, D'Mchwald. 

 (See ' General Introduction,' p. 135 ; and suprii, p. Gl.) 



Obolus (?) pltjmbeus, Salter (sp.). PI. L, figs. 23, 24. 



Obolella (?) plumbea, Salter. Vide supra, p. 61. 



While describing the exterior of Obolus {^.) plmnbeus at p. 61, I felt uncertain as to 

 the propriety of placing that species in Obolella. Since then, through the kindness of 

 Mr. Morton, of Liverpool, I have been able to examine the interior of one of its valves 

 (fig. 23) ; and this leads me to infer that the shell under notice is really more nearly 

 related to Obolus than to Obolella. 



