BRITISH SILURIAN BRACHIOPODA. 
OrtHis BILOBA, Lenneé (sp.). Pl. XXVI, figs. 10 to 15. 
Spee. Char. 
ANOMIA BILOBA, Linné. Systema Nature, ed. xii, vol. i, pars 2, p. 1154, 1767. 
TEREBRATULA SINUATA, J. Sow. ‘Trans, Linn. Soe., vol. xii, p. 516, pl. xxviii, figs. 5, 
6, 1815. 
— CARDIOSPERMIFORMIS, Hisinger. Anteck., Act. R. Soc. Holm., pl. vii, 
fig. 6, 1826. 
DELTHYRIS —_ Dalman. Vet. Akad. Handl., p. 124, pl. ui, fig. 7, 
1827. 
— — Hisinger. Bidrag till Sveriges Geognosi, vol. iv, 
p. 220, pl. vii, fig. 6, 1828. 
SPIRIFER — Von Buch. Ueber Spirifer und Orthis, Berlin 
Acad. Trans., p. 49, pl. i, fig. 7, 1837; and 
Mem. Soc. Géol. France, 1 ser., vol. iv, p. 196, 
pl. x, fig. 23, 1840. 
DELTHYRIS — His. Letheea Suecica, p. 74, tab. xxi, fig. 9, 1837. 
TEREBRATULA (DELTHYRIS ?) CARDIOSPERMIFORMIS, Angelin. Mus. Paleeont. Svecicum, 
1838. 
SPIRIFER sinuatus, Sow. Silurian System, p. 630, pl. xii, fig. 10, 1839. 
Detrnyris — J. Hall. Geol. Rep. 4th District New York, p. 105, fig. 8, 1843. 
Sprrirer ? BitoBa, Sharpe. Quart. Journal Geol. Soc., p. 161, 1847. 
— BILOBUS, De Vern. Bull. Soc. Géol. France, 2nd ser., vol. iv, 1847. 
OrtHIs BILOBA, Dav. Bull. Soc. Géol. France, 2nd ser., vol. v, p. 321, t. 3, fig. 18, 1848. 
— — De Verneuil. Ibid., p. 343, pl. iv, fig. 10, 1848. 
— — Phillips and Salter. Mem. Geol. Survey, vol. ii, p. 287, 1848. 
SPIRIFER BILOBUS, Bronn. Index Pal., p. 1173, 1848. 
Ortuis BILOBA, D’Orb. Prodrome, vol. i, p. 36, 1849. 
Dic@Losia BILOBA, King. Monog. Permian Fossils (Pal. Soc.), p. 106, 1850. 
ORTHIS — MCoy. Brit. Pal. Foss., p. 213, 1852. 
— CARDIOSPERMIFORMIS, Quenstedt. Handbuch der Petref., pl. xxxix, fig. 3, 
1851. 
SPrrireR BILOBUS, Hall. Pal. of New York, vol. ii, p. 260, pl. liv, fig. 1, 1852. 
OrTHIs BILOBA, Morris. Cat. of Brit. Foss., p. 139, 1854. 
Anomia — Hanley. Ipsa Linnzi Conchylia, p. 134, 1855. 
DELTHYRIS VARICA, Conrad. Journ. Ac. Phil., vol. viii, tab. xiv, fig. 20. 
OrTHIS BILOBA, Salter. Siluria, 2nd ed., p. 543, pl. ix, fig. 20, and pl. xx, fig. 14, 1859. 
— — Lindstrém. Gotl. Brach., Ofv. K. Akad. Forhandl., p- 370, 1860. 
oa — Ramsay and Salter. Mem. Geol. Survey, vol. iii, pp. 267, 361, 1866. 
— varica, Dana. Manual of Geology, p. 254, 1866. 
—  sriosa, Dav. Trans. Geol. Soc. Glasgow, Pal. Series, vol. i, pl. ii, fig. 11, 1868. 
Shell small, more or less deeply bilobed or forked, obcordate, sub- 
trigonal, constricted medio-longitudinally, deeply sinuate in front, widest anteriorly ; 
hinge-line straight, shorter than the width of shell. Dorsal valve moderately convex, 
umbone slightly gibbous, ears rectangular, flattened close to the cardinal extremities, 
