158 SUPPLEMENT TO THE 



Rough, near Minsterley, in Shropshire, where it is well characterised. It was also pro- 

 cured by Mrs. R. Gray in a formation of a similar age at Camregan Wood, in the Girvan 

 district in Scotland. 



48. Rhynchonella Weaveri, Salter. Dav., Sil. Mon., PI. XXIV, fig. 14; Sil. Sup., 



PI. X, figs. 24, 24 a. 



This species (?) from the Upper Llandovery is described at p. 185 of my ' Silurian 

 Monograph.' In the Upper Llandeilo, at Craighead, Ayrshire, Mrs. R. Gray collected 

 eight specimens of a Bhjnchonella which, notwithstanding its great difference in strati- 

 graphical position, I have ventured to class provisionally with Bh. Weaveri, 



In external shape it is somewhat sub-trigonal, six lines in length, by about five in 

 breadth, broadest anteriorly, tapering posteriorly ; dorsal valve moderately convex, and 

 ornamented Avith from eighteen to nineteen angular ribs, of which six form a slightly 

 raised mesial form ; ventral valve convex, with a shallow sinus ; ribs seventeen or 

 eighteen in number, of which five occupy the sinus ; beak incurved ; foramen small. 



49. Rhynchonella Jackii, Dav. Sil. Sup., PI. IX, figs. 30 a, b. 



Shell ovate, elongated oval, longer than wide ; valves almost equally convex ; dorsal 

 valve biplicated, fold large, slopes wide ; three ribs on each of the lateral lobes of the 

 valves, commencing at about the middle of the shell and extending to the front ; ventral 

 valve with a wide sinus divided by a narrow central elongated rib, commencing at about 

 half the length of the valve and extending to the front ; three ribs on each of the lateral 

 lobes of the valve ; beak small, incurved. 



Length 8, width 7, depth 5 lines. 



Obs. — Only one internal cast of this well-marked species was procured from the 

 Caradoc at Dunterleugh Burn, Wanlock Water, Leadhills district, Dumfriesshire. I 

 am assured that this is the specimen incorrectly identified as Merisiella angustifrons at 

 p. 15 of the Explanation of Sheet 15, 'Memoirs of the Geological Survey of Scotland,' 

 and it was kindly lent to me out of the Museum of the Geological Survey of Scotland 

 (Specimen M, 89^). 



I have named this species after Mr. R. L. Jack, now conducting the geological survey 

 of Queensland, who was the discoverer of the fossiliferous bands in the Leadhills 

 district of Scotland. 



Associated with Hh. JacJdi in the Leadhills district we find Leptcena sericea and 



