RHYNCHONELLID &. 193 
well as three drawings, of which I here append woodcuts. It is certain that the genus or 
species last named was provided with a tolerably long peduncle, for Mr. Billings found a 
silicified specimen (fig. a) at Paquette Rapids, on the Ottawa River, in the Black-River 
Limestone, in which this appendage had been wonderfully preserved. The fig. a represents 
the ventral valve, and the pedicle seems to issue from the back of the beak, as described 
above, although the inspection of the specimen kindly sent me by Mr. Billings would tend 
to leave some uncertainty in my mind how the pedicle could have found space sufficient 
to protrude from under the concave plate above described and seen in fig. B, which 
represents an enlarged view of the interior of the ventral valve, while in fig. c we have 
that of the dorsal one. From these figures the shell would appear to be destitute of 
teeth and sockets for the articulation of the valves, nor would there appear to exist any 
processes for the attachment of any appendage such as spiral arms, although I feel con- 
vinced that the shell was provided with them under some form at present quite unknown 
tous. Mr. Billings writes me that it seems to be allied to Lingula and Obolus ; but upon 
that point I would not venture, with the scanty material before me, to offer any decided 
opinion. No traces of muscular scars could be made out. 
Hicuwapia ? Capeweui, Dav. Pl. XXV, figs. 12—15. 
Pe TEREBRATULA CarewELLI, Davidson. Bull. Soc. Géol. France, 2nd series, vol. v, p. 327, 
pl iii, fig. 34, 1848. 
ATRYPA — D’ Orb. Prodrome, vol. i, p. 40, 1849. 
PORAMONITES — Morris. Catalogue of British Fossils, p. 143, 1854. 
RHYNCHONELLA — Salter. Siluria, 2nd ed., p. 250, 1859. 
PoRAMBONITES — Id. Ib., p. 544. 
— —  Lindstrém. Gotlands Brachiopoder, Ofv. K. Akad. Férhandl., 
p. 364, 1860. 
— — Murchison. Siluria, 3rd ed., p. 527, 1867. 
Spec. Char. Subrhomboidal, transversely oval, broadest anteriorly. Dorsal valve 
moderately convex ; mesial fold wide, rounded, and of small elevation ; commencing at a 
little distance from the umbone, it extends to the front. Ventral valve convex, rather less 
deep than the opposite one ; sinus broad, concave, and shallow ; originating at the extremity 
of the beak, it extends to the front ; beak small, closely incurved over the umbo of the 
dorsal valve. Surface of both valves closely covered with raised, thread-like ridges, forming 
all over the shell a network of more or less regular six-sided cells, the bottom of the 
cells being flat, and margined by slightly raised hexagonal ridges. In the interior of 
the dorsal valve there exists a mesial ridge, and a concave plate is present under the beak. 
In the dorsal valve a mesial septum extends from under the umbonal beak to about half 
25 
