Spirifer. 



MOLLUSCA. 



109 



throe central ones thicker and more elevated than the others, 

 and obscurely divided, the central into three and the others 

 into two ; back or lower valve flat, meeting the sides at an 

 acute angle; whole surface with fine, sharp, elevated, rather 

 distant, transverse strife. 



Figs. 3 and 4 represent the internal spiral appendages, from whence 

 the name of this genus is derived. 



Carboniferous Limestone, Derbyshire ; and the Mountain 

 Limestone in many localities. 



Section II Angustal.e — Cardinal line as wide as 



the shell; valves with incurved umbones; mesial fold 

 defined between two deeper furrows on the upper valve. 



12. Spirifer pyramidalis — The Pyramidal Spirifer, pi. 

 LI. fig. 7. 



Splrifera triangularis. Phillips, II. p. 2 1 7, pi. 9, fig. 1 2. 



Triangularly pyramidal ; mesial fold narrow ; umbo of lower 

 valve greatly produced, and inflected ; lower sides of the valves 

 acutely triangular, ending in a sharp base ; surface with from 

 seventeen to nineteen longitudinal, divergent, rather flattened 

 ribs, the central one considerably thicker than the others, the 

 lateral ones few in number. 



Mountain Limestone at BoUand, Kirby Lonsdale, and Der- 

 byshire. 



13. Spirifer rotundatus The Rounded Spirifer, pi. 



L. fig. 17, 18. 



Spirifer rotundatus. Sowerby, V. p. 89, pi. 461, fig. 1,1. 



Globose, transversely obovate ; cardinal area triangular, of 

 medium length, and not so long as the sides ; beaks incurved, 

 and approximating, that of the lower valve pretty large; middle 

 of the upper valve with a smooth, elevated ridge; whole surface 

 with rather depressed, longitudinal, divergent ribs, crossed at 

 intervals by nearly obsolete lines of growth ; cavity of the lower 

 valve with some obscure, longitudinal lines, but destitute of a 

 central division ; margins of the valves very sharp. 



Found in the Black Limestone at Limerick, Ireland. 



14. Spirifer Beanii. — Bean's Spirifer, pi. L. fig. 8. 



Spirifera rotundata. Phillips, II. p. 218, pi. 9, fig. 17. 



Beaks somewhat approximate ; cardinal area rather con- 

 tracted ; hinge line quite parallel, angular at the extremities ; 

 the sides bulging considerably from below the angles ; whole 

 surface with strong, radiating sulci ; mesial fold broad, nearly 

 smooth. 



Distinguished from S. rotundatus by the cardinal area being narrower, 

 and its extremities more acute. 



Mountain Limestone, Kildare, Bolland, and Queen's County. 



15. Spirifer octoplicatus The Eight-plaited Spirifer, 



pi. L. fig. 9, 10. 



Spirifer octoplicatus. Sowerby, VI. p. 120, pi. 562, fig. 

 2, 3, 4. 



Transversely elongated, semicircular, inflated; beaks remote; 

 cardinal area wide, curved, and triangular, with from eight to ten 

 deep, angular, longitudinal ribs or plaits, producing a strongly 

 crenulated margin ; mesial fold plain. 



The Mountain Limestone, Derbyshire. 



16. Spirifer pinguis The Plump Spirifer, pi. L. fig. 



13, 14. 



Spirifer pinguis. Sowerby, III. p. 125, pi. 271. Fleming, 

 p. 375. 



Gibbose, nearly globular, slightly transversely obovate ; beaks 

 rather close ; cardinal area shallow, not so wide as the shell ; 

 with eight or nine rounded, longitudinal ribs on each side of 

 the mesial fold ; groove in the lower side corresponding to the 

 mesial fold, but not sulcated ; intervening furrows rounded at 

 bottom. 



Black Rock Limestone of Ireland, 



17. Spirifer Walcottii Walcott's Spirifer, pi. L. fig. 



11, 12. 



Spirifer Walcottii. Sowerby, IV. p. 106, pi. 377, fig. 2. 



Suborbicular, both valves gibbose, smooth; cardinal area tri- 

 angular, shorter than the width of the valves ; umbo of the 

 larger valve pointed and incurved ; both beaks provided with 

 an angular foramen; mesial fold wide, rounded, with four rather 

 elevated, rounded, longitudinal ribs on each side. 



Found in the Lias at Camerton. 



18. Spirifer minimus — The Least Spirifer, pi. L. fig. 

 15, 16. 



Spirifer minimus. Sowerby, IV. p. 105, pi. 377, fig. 1. 



Transversely oblong, inflated, smooth, and subrhomboidal ; 

 umbones produced, and rather acute at the points ; cardinal area 

 long, flat; foramen between the umbones an elongated triangle; 

 surface with fifteen flat, longitudinal ridges, the three central 

 ones more elevated than the others, and but ill defined. 



Found in the Mountain Limestone near Bakewell, Derby- 

 shire. 



19. Spirifer striatus — The Striated Spirifer, pi. L. fig. 

 19, 20. 



Sjnrifer striatus. Sowerby, III. p. 125, pi. 270. Anomites 

 striata, Martin, Pet. Derb. pi. 23. Terehratula striata, Sower- 

 by, Linn. Trans. XII. p. 515, pi. 28, fig. 1, 2. Fleming, 

 p. 375. 



Transversely elongated, subcompressed ; cardinal area wide, 

 shallow, long, smooth, slightly striated, and acute at the sides ; 

 mesial sinus angular ; beaks of moderate length, and incurved ; 

 whole surface with numerous, longitudinal, narrow, irregular 

 ribs, and inequidistant lines of growth. 



The Mountain Limestone of Derbyshire and Cork. 



20. Spirifer bisulcatus. — The Two-furrowed Spirifer, 

 pi. L. fig. 21,22. 



Spirifer bisulcatus. Sowerby, V. p. 152, pi. 494, fig. 1, 2. 

 Fleming, p. 375. 



Gibbous, semicircular, its width but slightly exceeding its 

 length ; cardinal area long, straight, with parallel sides, caused 

 by the edges of it upon the deeper valve being reflected; beaks 

 rather prominent, curved, and nearly meeting ; a deep furrow 

 on each side of the mesial ridge ; the whole surface with about 

 thirty rather regular, longitudinal ribs, two on each side, near 

 the centre, considerably deeper than the others, with the 

 intervening spaces frequently convex, although they are flat in 

 some. 



Carboniferous Limestone, neighbourhood of Dublin. 



21. Spirifer attenuatus — The Attenuated Spirifer, pi. 

 L. fig. 25, 26. 



Spirifer attenuatus. Sowerby, V. p. 151, pi. 493, fig. 3, 4, 

 5. Fleming, p. 375. 



Convex, transversely elongated, its breadth more than double 

 its length; cardinal area long, straight, with nearly parallel 

 edges ; sides produced, and acute ; beaks short, and but little 

 2 E 



