146 DEVONIAN FAUNA. 
by its cordate section, and especially by its coarse triangular ribs. The nearest 
approach to it which I have seen is a specimen of Orthis hybrida in Dr. Davidson’s 
Collection, but its ribs are very much coarser than those of that shell. It appears 
to belong to the group Schizophoria. 
3. Genus.—Ortnortetses, Fischer de Waldheim, 1830. 
SrrepToruyncuvus, King, 1850. 
Waagen, Hall, Hhlert, and others restrict Streptorhynchus to shells with a high 
triangular area and shorter hinge-line, which belong to newer Paleozoic formations. 
In view, however, of the extreme variation of the height and width of the area in 
O. distortus, it seems to be impossible that these points can here have generic 
importance. Hall’ having, however, proved that Fischer’s name has priority, I 
substitute it, though with great regret, for the more usual appellation of the 
genus. Davidson,’ quoting Waagen, had left the question of priority open; at 
the same time suggesting that Orthotetes, Streptorhynchus, and Derbyia may prove 
congeneric. 
1. OrTHoTETES UmBRACULUM, Schlotheim, sp. 
1820. TEREBRATULITES UMBRACULUM, Schlotheim. Petref., p. 256. 
1843. Orrnis umBRacuLuM, F. A. Romer. Verst. Harzgeb., p. 11, pl. iv, fig. 4. 
1864. SrREPTORHYNCHUS UMBRACULUM, Davidson. Brit. Foss. Brach., vol. iii, 
pt. 6, p. 76, pl. xvi, fig. 6, 
and pl. xviii, figs. 1—5. 
1882. — UMBRACULUM, Barrois. Mém. Soc. Géol. Nord, vol. ii, 
p. 239, pl. ix, fig. 2. 
1886. — CRENISTRIA, Stuckenberg. Mém. Acad. Imp. Sci. St. 
Pétersbourg, ser. 7, vol. 
xxxiv, No. 1, p. 6, pl. iii, 
figs. 1—5. 
1886. _ uUMBRACULUM, Wenjukoff. Fauna Dev. Syst. N.W. und 
Central Russl., p. 469, pl. u1, fig. 15. 
1887. —_ — Bechard. Bull. Soc. Belge Géol., vol. i, 
p. 86. 
1887. OrrHoTHETES UMBRACULUM, @hlert. In Fischer’s Manuel Conch., p. 1285, 
fig. 1049. 
? 1892. — Wootworrniana, Hall. Pal. N. Y., vol. viii, pl. ix, figs. 
25—31. 
1 1892, Hall, ‘Pal. N. Y.,’ vol. viii, pt. 1, p. 256. 
2 1884, Davidson, ‘ Brit. Foss. Brach.,’ vol. vi, p. 379. 
