62 DEVONIAN FAUNA. 



Affinities. — Aclisina longissima seems distinguislied by its raucla more aciculate 

 form, and more numerous threads, and by the absence of transverse lines and 

 sinus-band. 



Loxonema gracillimum, Whiteaves,^ is a longer shell with broader whorls, 

 direct transverse threads and no sinus-band. 



M. bistriata, F. A. Romer,^ seems longer and more conical, and has only two 

 spiral threads. As given by Geinitz,^ it is much more like our shell, but is described 

 as having only three spiral threads. 



VII. Family — Bellerophontid^, M'Coy, 1851. 

 1. Oenus — Bellerophon, de Montfort, 1808. 

 1, Bellerophon (Bucania) elegans, d'Orbigny. PI. VII, figs. 1, 1 a. 



1840. Belleeophon elegans, de Ferussac and d^Orhigny. J>Jat. Hist. Ceph., 



p. 203, (Bellerophon) pi. vii, figs. 15—18. 

 ? 1840. — CLATHRATUS, de Ferussac and d'Orhigny. Ibid., p. 204, pi. v, 



figs. 24—27, and pi. vii, figs. 12—14. 

 ? 1842. — ELEGANS, d'Archiac and de Verneuil. Geol. Trans., ser. 2, 



vol. vi, pt. 2, p. 354, pi. xxix, figs. 2, 2 a, 

 ? 1843. — DEcirssATUS, de Eoninch (pars). Desc. Anim. Foss. Carb. 



Belg., p. 339, pi. xxix, fig. 3, and pi. xxx, fig. 3. 



1848. — ELEGANS, Bronn. Index Palseont., p. 163. 



1849. — DECtrssATUS, d'Orligny (pars). Prod., vol. i, p. 126. 



? 1883. Bucania elegans, de Koninch. Ann. Mus. Roy. H. N. Belg., vol. viii, pt. 4, 



p. 151, pi. xli, figs. 18—21. 

 ? 1883. — Abchiaci, de KonincJe. Ibid., p. 151. 



Description. — Shell small, discoid, rather flat. Aperture expanded. Whorls 

 convex, rather obliquely flattened on the sides, and rapidly curving in round the 

 umbilicus. Keel large, elevated, sub- triangular or rounded. Umbilicus open. 

 Surface ornamented with distant, strong, rather unequal, radiating threads, crossed 

 by finer and closer arching threads or lines of growth. 



Size. — About 2*5 mm. wide and 2*5 mm. high. 



Locality. — One tiny specimen from Pilton is in the Porter Collection. 



BemarJcs. — Our specimen is decoriated, and partly embedded in matrix. The 

 striae are clear near the mouth, but the ornament of the keel cannot be traced. 

 It is possible from its small size and general appearance that it may be a young 

 shell. 



1 1892, Whiteaves, ' Contr. Canad. Pal.,' vol. i, pt. 4, p. 337, pi. xlv, fig. 10. 



2 1850, F. A. Eomer, ' Beitr. Harzgeb.,' pt. 1, p. 37, pi. v, fig. 26. 



^ 1853, G-einitz, ' Verst. Grauw. Sachsen,' pt. 2, p. 42, pi. xi, fig. 9. 



