174 BRITISH SILURIAN BRACHIOPODA. 
Obs. Of this species I have seen but two or three examples, and consequently it 
is not possible to say much with reference to the modifications it may assume. It does not 
appear, however, to be very rare in the Caradoc Limestone of Craig Head, near Girvan, in 
Ayrshire, from whence Prof. M‘Coy’s original specimen was derived, but it is difficult 
to obtain out of that rock a perfect specimen. One, however, of which the dorsal valve 
was almost entire, did not present so elongated a form as is presented by the typical 
specimen in the Cambridge Museum. It would consequently be desirable that more 
specimens of this shell should be collected by those who may have occasion to 
visit the Craig Head Quarry. Prof. M‘Coy informs us that this species much resembles 
the Zerebratula promontorium of Kutorga, from the Lower Silurian limestones of Pulkowa 
(see ‘ Verhandlungen der Russ. Kais. Min. Gesellschaft zu St.-Petersburg,’ for 1845, 
pl. vi, fig. 3), but is distinguished by its ribbed surface. 
RHYNCHONELLA BOREALIS, Schloth. Pl. XXI, figs. 14—27. 
? ANOMITES PLICATELLA, Wahlenberg. Nov. Act. Upsal., p. 67 (Linn., Mus. Tessin., 
p- 88, pl. v, fig. 57), 1821. 
TEREBRATULA — Dalman. Vet. Akad. Handl., p. 140, pl. vi, fig. 2, 1828 
(synonymia exclusa). 
— DIODONTA, Td. Ib., pl. vi, fig. 4, 1828. 
— BOREALIS, Id. Schlotheim, Systematisches Verzeichniss der Pet. 
Sammlung, p. 68, No. 88, 1832. 
— —- V. Buch. Ueber Tereb., Akad. Berlin, p. 67, 1834; and 
Mem. Soc. Géol. de France, vol. iii, p. 171, pl. xvi, 
fig. 15, 1838. 
oo PLICATELLA, Hisinger. Letheea Suecica, p. 80, tab. xxiii, fig. 4, 1837. 
— BOREALIS, Angelin. Mus. Pal. Suecicum, No. 48, 1838. 
—- LACUNOSA (= 7’. borealis, Schloth., Buch), J. de C. Sowerby. Sil. Syst., 
pl. xii, fig. 10, 1839. 
— BIDENTATA, Sow. Ib., pl. xii, fig. 13a. 
— PLICATELLA, De Verneuil. Geol. of Russia, vol. ii, p. 84, 1845. 
= — Td. Bull. Soc. Géol. de France, vol. v, 2nd ser., 
p. 346, 1848. 
— CRISPATA, Dav. Ib., p.329 (non T. crispata, Sow.) 
HyPoTHYRIS BOREALIS, Phillips and Salter. Memoirs Geol. Survey, vol. ii, p. 383, 
pl. xxviii, figs. 9—14, 1848. 
TEREBRATULA —  Bronn. Index Pal., p. 1231, 1848. 
Hemituyris —  DOrbigny. Prodrome, voi. i, p. 37, 1849. 
RHYNCHONELLA — Morris, Cat. of British Fossils, p. 146, 1854. 
HEMITHYRIS LAcUNOSA, M‘Coy. Brit. Pal. Foss., p. 201, 1852. 
RHYNCHONELLA —  Schmidé. Sil.-Form. Ehstland, &c., Archiv. Nat. Liv.- Ehst- und 
Kurland, vol. ii, p. 211, 1858. 
= PLICATELLA, D’Hichwald. Lethzea Rossica, vol. i, p. 758, 1859. 
