TEMNODISCUS MURCHISONI. 49 



backwards obliquely to meet carina at 75° — 60°, with their edges rising' into small 

 nodules where crossed by the strong - regular contiguous revolving ridges of equal 

 size and strength ; lamellas frequently alternate on opposite sides of whorl. 



Dimensions [G. 80486]. — Height of shell 10 mm. ; height of mouth 6 mm. ; 

 width of mouth 4 nun. 



Horizon. — Wenlock Limestone. 



Localiti/. — Dudley. 



Remarks. — The single specimen in the British Museum [G. 8048G], on which 

 the foregoing description is based, has much of the proximal part of the shell 

 hidden by the matrix and b} r an attached specimen of Orbiculoidea. The presence 

 of a slit-band is only visible near the mouth, and proximally its edges draw 

 together so that it seems to be closed. The shell, however, must be referred to the 

 genus Temnodiscus rather than Oyrtolites, and is allied to T. lamellifer (Lindstr.) 1 

 and T. pharetra (Lindstr.). 2 



3. Temnodiscus murchisoni (D'Orbigny). Plate IX, figs. 8, 9. 



1839. Bellerophon striatus, Sowerbv (non Broun, 1835), in Murchisou's Silurian System, p. 604, pi. iii, 



fig. 12 e. 

 1848. Bellerophon murchisoni, Ferussac and D'Orbigny, Hist. Nat. Ceph., vol. i, p. 210, pi. vii, 



figs. 1-3. 

 1852. BeUerophon murchisoni, D'Orbigny, M'Coy, Syu, Brit. Palseoz. Toss. Woodw. Mus., fasc. ii, 



p. 310. 

 non 1842. BeUerophon murchisoni, D'Orbigny, D'Arcliiac and de Verneuil, Trans. Oeol. Soc. [2], 



vol. vi, p. 353, pi. xxviii, figs. 7, 8. 



Specific Characters. — Shell somewhat compressed, carinated, increasing very 

 rapidly in size towards the mouth, especially in height; composed of few (1 — 2) 

 whorls. Outer whorl higher than wide, subcordate, with dorsum acutely angular, 

 becoming subangular towards mouth and finally almost rounded, the sides of the 

 whorl becoming at the same time more convex and swollen and the whole whorl 

 broader ; carina slightly raised, with flattened top bearing slit-band [with widely 

 separated strongly arched lunulas]. Umbilicus situated considerably below centre 

 of shell, small, open, perforated (?). Surface of shell ornamented with numerous 

 closely placed, sharp, thin transverse lines or lamellge [having finely fimbriated 

 edges], bending back rather suddenly to meet the carina at about 30° — 45°. 



Dimensions. — Height about 12 mm. [6669.] 



Horizon .—Upper Ludlow . 



Localities. — Felindre; Horeb Chapel, Llandovery; Malvern. 



Remarks. — There has been considerable confusion about this species, but the 

 above description has been drawn up from the type-specimen in the Jermyn 



1 Lindsti'om, op. cit., p. 82, pi. vi, figs. 31 — 38. 



2 Ibid., p. 83, pi. vi, figs. 39—51. 



