Spirifer. 



MOLLUSCA. 



115 



83. Spirifer disjunctus — The Disjoined Spirifer, pi. 

 LII.* %. 48. 



Sphijira disjuncta. Sowerby, Geo. Trans. V. 2nd series, 

 pi. 53, Rl'. 8, and pi. 54, fig. 12, 13. 



Very convex, semicircular ; base emarginato ; upper valve 

 with about twelve divergent, pretty strong ribs, raised in front, 

 producing a rounded elevation ; lower valve with numerous, 

 rounded ribs, about twenty-five on each side of the mesial one; 

 hinge area broad, curved, with nearly parallel edges; beaks 

 remote. 



Differs from S. bisulciita, pi. L. fig. 21, 22, in being less convex, and 

 in its more numerous itria;, with its liinge line broader. 



Found in the Devonian Shale at Potherwin and Barnstaple. 



84. Spirifer pabtitus. — The Divided Spirifer, pi. LII.* 

 fig. 50, 51. 



Spirifera partita. Portlock, Geo. Rep. p. 567, pi. 38, 

 fig. 3. 



Round; lower valve with a deep sinus, extending to the base ; 

 the opposite valve with a corresponding rib ; the furrows and 

 ribs, between which and the sides are strongly marked, vary in 

 number from three to six. 



Approaches iu form to *S. speciosus^ fig. 24, 25. 



Found in the Carboniferous Limestone at Kildress, Ireland. 



85. Spirifer simplex. — The Simple Spirifer, pi. LII.* 

 fig. 49 and 58. 



Spirifer simplex. Phillips, Pal. Fos. p. 71, pi. 29, fig. 

 124. 



Pyramidal ; cardinal area very large, triangular ; mesial rib 

 with obtuse borders; triangular foramen narrow, reaching to the 

 point of the beak in the larger valve ; smaller valve convex ; 

 destitute of ribs or furrows. 



Found in the Devonian Shale at Plymouth and Newton, 

 South Devon. 



86. Spirifer l^vis The Smooth Spirifer, pi. LII.* 



fig. 52. 



Spirifer Icevis ? Sowerby, Sil. Syst. p. 638, pi. 21, fig. 12. 



Transversely elongated, semicircular, smooth, compressed ; a 

 slight obsolete rib along the middle ; beaks of umbones pro- 

 minent, divided by a narrow area, with parallel edges. Length 

 eight lines; breadth double ils length. 



Found in the Lower Silurian Rocks at Noeth-grag ; Land- 

 overy; May Hill, Gloucestershire; Gullet Wood, Estnor Park, 

 and Hope Hill, Salop. 



87. Spirifer calcaratus. — The Spur Spirifer, pi. LII.* 

 fig. 53. 



Spirifer calcaratus. Sowerby, Geo. Trans. V. 2nd series, pi. 

 53, fig. 7. Phillips, Pal. Fos. pi. 29, fig. 128. 



Transversely elongate, semicircular ; sides very convex, pro- 

 duced, cuspidate, smooth, with longitudinal sulci ; front hardly 

 elevated ; with numerous rounded ribs, about nine on the front 

 circumscribed by two deep furrows ; cardinal area very narrow. 

 Width double its length. 



Distinguished from S. altenuata, pi. L. tig. 25, 26, by the sudden 

 contraction of the sides, and the very slight elevation in front. 



88. Spirifer Urii Ure's Spirifer, pi. LII.* fig. 54, 55. 



Spirifer Urii. Fleming, Brit. An. p. 313. Ure, Ruth, and 



Kil. p. 313, pi. 14, fig. 12. Spirifer Uiiguiculus, Phillips, Pal. 

 Fos. p. 69, pi. 28, fig. 119. Alrypa C/nguiculus, Sowerby, 

 Geo. Trans. V. 2nd series, pi. 54, fig. 8. 



Hemispherical, somewhat wider than long, smooth, with the 

 beak inflated ; base emarginate ; lower valve very convex, with 

 its beak channelled; upper valve compressed, with a central im- 

 pressed line. 



Found in the Devonian Shale at Petherwin, near Barnstaple. 

 Pilton, Brushford, and Ruthcrgleu, Renfrewshire. 



89. Spirifer nudus. — The Naked Spirifer, |)l. LII.* 

 fig. 56. 



Spirifer nuda. Sowerby, Geo. Trans. V. 2nd series, pi. 57, 

 fig. 8. 



Semicircular, with the beaks prominent and smooth ; a mesial 

 rib, with a furrow on each side ; margin obtuse. 



Found in the Devonian Shale at Plymouth. 



90. Spirifer plicatus — The Plaited Spirifer, pi. LII.* 

 fig. 57. 



Spirifer plicatus. Sowerby, Sil. Syst. p. 638, pi. 21, fig. 6. 



Transversely elongated, semicircular, convex; with numerous, 

 radiating, sharp plaits, which are narrow above, and become 

 wider towards the base; beaks contiguous; cardinal area narrow; 

 hinge line nearly double the length of the valves. Length 

 eleven fines ; width one inch and seven lines. 



Found in the Lower Silurian Rocks at Goleugoed, Llan- 

 dovery. 



Genus IV.— GYPIDIUM.— 5o(ie/%. 



Shell inequilateral, inequivalve ; the larger valve with 

 an incurved umbo, remote from the hinge; the larger 

 valve divided by a central suptum into two parts ; the 

 other by two parallel, approximate septa into three un- 

 equal parts ; umbones imperforate, and incurved. 



1. Gypidium Aylesfordii. — Aylesford's Gypidium, pi. 

 XLIX. fig. 31,32. 



Pentamerus Aylesfordii. Sowerby, T. p. 75,* pi. 29. Fle- 

 ming, p. 378. 



Almost orbicular ; with rather strong, longitudinal ribs, the 

 intervening furrows narrow below ; larger valve more inflated 

 than the other, with a prominent, greatly incurved beak. 



In the young condition the umbones are not so different in size, as in 

 the adult, and they are proportionally more approximate. 



Carboniferous Limestone, Colebrookdale; and in the Ames- 

 try Limestone, Croft Ambery Park, and Yeo-edge. 



2. Gypidium Knightii. — Knight's Gypidium, pi. XLIX. 

 fig. 2. 



Pentamerus Knightii. Sowerby, I. p. 73,* pi. 28, upper 

 figure. Fleming, p. 378. Murchison, Sil. Syst. p. 615, pi. 6, 

 fig. 8, a, h, c. 



Suborbicular ; one valve small, the other large, with a long, 

 considerably incurved beak; surface with numerous, strong, 

 rounded, longitudinal ribs, crossed by inequidistant lines of 

 growth ; cardinal area smooth, and triangular. 



The Amcstry Limestone at View Edge, Ludlow ; Amestry ; 

 Sedgeley, near Dudley; Dowton-on-the-Rock, and Yeo-edge. 



3. Gypidium l.evis. — The Smooth Gypidium, pi. XLIX. 

 fig. 39, 40, 41,42, 43. 



Pentamerus Icevis. Sowerby, I. p. 76,* pi. 28, right hand 

 figure. lb. Sil. Syst. p. 641, pi. 19, fig. 9. Fleming, p. 378. 



