638 SHELLS OF THE LOWER SILURIAN ROCKS. 



Spirifer radiatus s var., PL 21. f. 5. The beak of this variety is not curved as in the ordinary form 

 of S. radiatus. 



Loc. Castell craig-gwyddon, Llandovery. 

 Spirifer plicatus, PI. 21. f. 6. Semicircular, convex, sharply plaited, especially towards the margin ; 

 beaks near each other, hinge line nearly double the length of the shell. Length 11 lines, width 

 1 inch 7 lines. 



Loc. Goleugoed, Llandovery ; Bala f 

 Spirifer alatus, PI. 22. f. 7« Semicircular with expanded cuspidate sides, plaited, slightly raised 



in the middle ; plaits about 18, acute. Length 5| lines, width 9J- lines. 



Loc. Pensarn and Mount Pleasant, Caermarthen. 

 Spi?nfer liratus, PI. 22. f. 6. This represents the distorted cast of a large Spirifer or Or this. 



Length nearly 3 inches. 



Loc. Marloes Bay, Pembrokeshire. 

 Spirifer f Icevis, PI. 21. f. 12. Semicircular, compressed, smooth 5 a slight elevation along the 



middle ; beaks rather prominent, the area between them narrow with parallel edges. Length 



8 lines, width twice as much. 



In general form this shell approaches to that of Orthis. 



Loc. May Hill r Gloucestershire ; JVoeth-grug, Llandovery ; Gullet Wood, Eastnor Park ; 

 Hope Mill, Salop ; Loiver Lickey [overlying beds) . 

 Orthis grandis, PL 20. f. 12 and 13. Semi-oval, short, nearly flat, irregularly radiated within j 



radii numerous, forked. Length about 1| inch, width nearly 2 inches. 



Having only seen impressions of the interior of this fine shell ; the description, as in many 



similar cases, is necessarily incomplete. 



Loc. Horderley j Acton Scott ; and Jlank of Caradoc. 

 Orthis expansa, PI. 20. f. 14. Semicircular, flat, internally plaited near the margin ; muscular im- 

 pression deeply furrowed. Length 1 inch 7 lines, width 2 inches. 



Loc. Moel-y- Garth and Gaerfaivr, near Guilsjield. 

 Orthis alternata, PI. 19. f. 6. Transversely obovate, finely radiated ; one valve convex, the other 



flat or concave; radii extremely numerous, of unequal fineness and increasing in number towards 



the edge ; hinge line shorter than the width of the shell. Length 10 lines, width 13 lines. 



Loc. Whittingsloiv ; Soudley j and east Jlank of the Caradoc ; Alt-yr-ankr ; and the Maen 

 Meifod; Loiver Lickey Ridge ; east Jlank of Berwyns ; Mandinam, Llandovery. 

 Orthis compressa, PL 22. f. 12. Lenticular, compressed, with a straight hinge line j striato-punc- 



tated throughout its substance. Length 1 inch j width 14 lines. 



Loc. Hope Quarry, near Shelve, Salop. 

 Orthis protensa, PL 22. f. 8 and 9. Semioval, depressed, radiated; radii linear, sharp, unequal in 



thickness. Length 8 lines, width 7 lines. 



Loc. Goleugoed; Meadow Town, near Shelve ; Berwyns. 

 Orthis anomala, PL 21. f. 10. (Anomites anomalies, Schl. Nacht. Pet. 1. p. 65. t. xiv. f. 2.) Ob- 

 long with straight sides, convex, striated. Length 1 inch 7 lines, width 1 inch 5 lines. 



Only one valve has fallen under our observation, we are not sure therefore that the margin 



would be like that in Schlotheim's figure. 



Loc. Horderley; east Jlank of Caradoc ; east Jlank of Berivyns. 

 Orthis Pectenf, PI. 21. f. 9. (Balm. I. c. p. 110. t. i. f. 65 His. Pet. Suec. p. 70. t. xx. f. 6.) 

 Semi-oval, short, convex, finely radiated ; radii nearly equal, cut by the lines of growth ; hinge 



