52 ORDOVICIAN AND SILURIAN BELLEROPHONTACEA. 



Remarks. — Only the single specimen [G. L7506] of this species in the British 

 Museum is known to me. It is allied to T. lamellifer (Lindstr.), 1 but differs in 

 the transverse ribs not being lamellose or fimbriated and by their inclination to 

 the keel being more at right angles, as well as by the interspaces being smooth 

 and by the whorl increasing less rapidly in size 



5. Temnodiscus solitarius, sp. now Plate IX, fig. 11. 



Specific Characters. — Shell high, narrow, compressed, cornuate, composed of 1 1 

 whorls in contact, but not overlapping; inner whorls absent, leaving umbilicus 

 perforated. Whorls lanceolate in cross-section, rapidly increasing in height, more 

 than twice as high as wide, with gently convex sides, and high compressed carina 

 bearing narrow slit-band on summit. Mouth simple. Umbilicus small, open. 

 perforated, situated at about one-fourth the height of shell. Surface of whorls 

 ornamented with regular equidistant thick transverse lines, closely placed, 

 fimbriated minutely and set with transverse granules connected with fine lines 

 across interspaces, arched gently back on sides, lint more strongly near carina, 

 where they become finer and closer and meet slit-band at about 30°. Slit-band 

 narrow, not clearly defined, crossed by strong lunulas. 



Dimensions. — Height of shell about 11*5 mm. 



Horizon. — Upper Ludlow (Whitecliffe Group, 8p. eh vatus Beds). 



Locality.- — Ludford Lane. 



Remarks. — This shell, which was recorded as Bellerophon murchisoni by Misses 

 LUes and Slater, 2 resembles T. lamellifer (Lindstr.), the type of the genus, in shape 

 and perforated umbilicus, but in ornament is more like T. arrosus (Lindstr.) 3 and 

 T. pharetra (Lindstr.). 1 There is no described British species like it. 



Genus BELLEROPHON, Montfort (sens. str.). 



Generic Characters. — Symmetrically involute, subglobose shells, with or without 

 an umbilicus, the latter never very large in the typical section, whorls more or 

 less rounded on the back; aperture generally expanded, usually with a callosity 

 on the inner lip ; dorsal lip with a more or less deep central emargination behind 

 which there is a well-developed slit-band; surface sculpture consisting of more 

 or less strongly-developed transverse stride of growth. Type, //. oasulites, 

 Montfort,"' 



1 Lindstrom, op. cit., p. 82, pi. vi, figs. 31 — 38. 



2 Elles and Slater, 'Quart, Jonrn. Geol. Soc.,' vol. lxii (1906), }<. 219. 

 8 Lindstrom, op. cit., p. 83, pi. vi, figs. 52 — 53. 



1 Ibid., p. 83, pi. vi, figs. 39—51. 



5 Montfort, 'Conchyl. System.,' vol. i (1808), p. 51. 



