56 ORDOVICIAN AND SILURIAN BELLEROPHONTACEA. 



4. Bellerophon sphaera, Lindstrom, var. now judex. Plate IX, fig-. 15. 



Varietal < Characters. — Shell globose, involute, outer whorl completely enveloping 

 inner whorls; umbilicus closed, central. Whorls rounded, wider than high; 

 dorsum and sides convex, more or less inflated. Slit-band narrow, slightly 

 elevated. Mouth slightly expanded, transversely semi-elliptical, with the lower 

 lip slightly reflected and adherent. Surface of shell crossed by gently arched 

 fine striae of rather irregular size meeting slit-band at acute angle (30° — 45°). 



Dimension*. — Height of shell, 35 mm. ; thickness at umbilicus c. 22 mm. ; 

 width of mouth, c. 40 mm. 



Horizons. — (1) Mulloch Hill Group, Lower Llandovery. (2) Saugh Hill 

 Group, Upper Llandovery. 



Localities. — (1) Mulloch Hill, Girvan ; (2) Woodland Point, Girvan. 



Remarks. — The general characters of this shell seem to show that it is 

 specifically inseparable from B. sphaera, Lindstr., 1 but the less coarse and less 

 regular ornamentation may be regarded as sufficient to put it as a variety. 

 The absence of catenation of the dorsum and the different ornamentation show 

 that we cannot refer it to B. wenlockensis. As in the case of the Gotland 

 shells there seems to be some variation in the globosity of our specimens, but the 

 Woodland Point examples are too much crushed to determine their original shape. 



5. Bellerophon wenlockensis, Sowerby. Plate IX, fig. 16. 



1839. Bellerophon wenlockensis, Sowerby, in Mnrchisoii's Silurian System, p. 033, pi. xiii, tig. 21. 

 (Non 1841. Bellerophon wenlockensis, Sowerby ? Phillips, Palseoz. Foss. Cornw. Dev., p. 108, pi. xl, 



fig. 203.) 

 1848. Bellerophon wenlockensis, Sowerby, Ferussac and d'Orbigny, Hist. Nat. Ceph., vol. i. p. 189, 



pi. viii, fig. 7. 

 1852. Bellerophon wenlockensis, Sowerby, McCoy, Syu. Brit. Pal. Foss. Woodw. Mus., p. 311. 

 1875. Bellerophon wenlockensis, Sowerby, Baily, Charact. Brit. Foss., vol. i, Palaeoz., p. 65, pi. xxii. 



fig. 2. 

 1884. Belleroplion wenlockensis, Sowerby. J. I). La Touebe, Handbook to the Geology of Shropshire, 



p. 73, pi. xiv, fig. 492. 



Specific Characters. — Shell subglobose to globose, involute, outer whorl nearly 

 completely embracing inner whorls. Umbilicus small, deep, nearly concealed by 

 downward extension of lateral angles of mouth. Outer whorl slowly increasing in 

 size, very transverse, more than twice as wide as high, sides rounded, inflated; 

 dorsum convex, rounded, except near mouth, where a low sharp narrow keel is 

 developed. Slit-band narrow, raised, with sharp elevated edges and numerous 



1 Lindstrom, op. fit., p. 74, pi. iii, figs. 35 — 38 ; pi. v, fig. 1 — 16. 



