ORTHOTETES. 147 
Localities.—Highteen specimens from Lummaton, and one from Wolborough 
are in my Collection; three from Lummaton, and four from Wolborough in the 
Torquay Museum ; five from Wolborough in Mr. Vicary’s Collection; three from 
Wolborough in the British Museum. 
Remarks.—My Lummaton specimens are of large size, but do not preserve the 
minor transverse striz. Wolborough specimens are frequently of the form of 
moulds, retaining, however, the outer layer of shell, and the ribs are in that case 
so deeply impressed as to give a very different aspect to the fossil. Davidson, 
however, evidently regards them as all belonging to the present species, and 
none of the fossils that I have seen give any evidence to shake this view or to 
add to the details of his description. 
From Strophomena pecten it is distinguished by the broader hinge-area and 
larger pseudo-deltidium of the ventral valve, and by the linear hinge-area without 
any pseudo-deltidium of the dorsal valve. The question of the identity of 
St. crenistria still remains where Davidson left it. 
The ornament in the various varieties of O. Chemungensis, Conrad,’ seem finer 
and more even, and the internal marks different. 
2. OrtTHoTETES pistortus, Barrande, sp. Pl. XVII, fig. 2. 
1879. Orruts pistorta, Barrande. Syst. Sil. Bohéme, vol. v, pl. lviii, figs. 4—5/f, 
pl. lx, fig. 4,1-9; pl. evii, fig. 6; pl. exxvii, 
fig. 2,1, Et. F. 
1887. SwrREPTORHYNCHUS UMBRACULUM, var. ToRTA, @hlert. Ann. Sci. Géol., 
vol. xix, p. 57, pl. iv, figs. 24—28. 
1889. Orruis pistorta, Whidborne. Geol. Mag., dec. 3, vol. vi, p. 78. 
Description.—Shell rather small, sub-convex, very much distorted. Beak 
rather prominent, laterally twisted. Surface covered by very numerous alter- 
nating, distant, rounded, elevated ribs, the interspaces between which become 
wider as they reach the margins. 
Size.—Length, 17 mm.; width, 20 mm.; depth, 12 mm. 
Locality.— There are two specimens in my Collection from Lummaton. 
Remarks.—This shell is chiefly remarkable for the extreme irregularity of its 
shape. It was first identified in my Collection by Mr. Marr, and a comparison, 
made by him, with Bohemian fossils in the Woodwardian Museum({left no doubt of 
its identity with Barrande’s species. 
1 1867, Hall, ‘ Pal. N. Y.,’ vol. iv, pt. 1, p. 67, pls. iv, ix, and x. 
