Lamdson — Earliest British Brachiopoda. 311 



moderately convex and marked by concentric lines of growth. 

 Lower Trcmadoc, Craig-y-dinas, North Wales. The internal cha- 

 racters agree pretty closely with those already described in 0. 

 Sagittalis. 



Obolella maculata, Hicks, M.S. PL XVI. Figs. 1-3. 



Report Brit. Assoc, (p. 285), 1865. 



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. 



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

 internal characters of this interesting fossil. I have, however, at- 

 tempted to draw what little was clearly observable of its interior. 

 0. maculata differs considerably from 0. Sagittalis, both 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 

 named, and is often found in a much compressed or flattened state in 

 the rock in which it is imbedded. 0. maculata was found by Mr. 

 Hicks to occur chiefly in the middle portion of the ' Menevian 

 Group ' at Porth-y-rhaw, St. David's. Mr. Belt obtained it from the 

 ' Lower Menevian ' at Camlan, and in the lower portion of the group 

 at Gwynfynydd in North. Wales. 



Obolella r Salteri, Holl. PL XVI. Figs. 8 and 9. 



With reference to the genus to which this apparently rare species 

 should be referred, some uncertainty must still prevail, for we have 

 not yet seen its interior. It has been stated to occur in the ' Upper 

 Lingula flags ' in the Malvern district. Mr. Belt has also found 

 some specimens which I cannot distinguish from 0. ? Salteri in the 

 ' Lower Tremadoc ' at Craig-y-dinas, in North Wales. There would 

 be nothing improbable in this species having passed from the Ffes- 

 tiniog group into the overlying ' Tremadoc ' one. 



Genus Obolus, Eichwald, 1829. 



Obolus ? plumbea, Salter. Var. ]olicata, Hicks, M.S. PL XVI. 

 Figs. 6 and 7. 



While describing the exterior of Ohohs ? phimlea at p. 61 of my 

 Silurian monograph, I felt very uncertain as to the propriety of 

 locating it with Obolella ; since that period, through the kindness of 

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

 of one of its valves (PL XVI. Fig. 5), and which leads me to infer 

 that the shell under notice is more nearly related to Obolus than to 

 Obolella?. 



After a lengthened study and comparison of a smaller form sent to 

 me by Mr. Hicks under the designation of Ob. plicata, which occurs 

 sparingly in the ' Lower Arenig or Skiddaw group ' at Tremanhire 

 and Ramsay Islands, near St. David's, in South Wales, I could not 

 divest myself of the idea that this last w^as nothing more than a 

 smaller variety of the typical form which occurs in the 'Upper Arenig' 

 and ' Lower Llandeilo ' rocks of North Wales. In external shape 



