192 BRITISH SILURIAN BRACHIOPODA. 
RuyNcHoNnELLA P NANA, Salter, MS. Pl. XXIV, fig. 26. 
Spec. Char. Shell small, obscurely pentagonal, broadest near the beaks, gradually 
narrowing anteriorly, slightly indented in front. Ventral valve very convex, and keeled 
along the midale, but divided by a small longitudinal groove or sinus, most apparent near 
the front; lateral portions of the valve slightly concave, beak incurved. Dorsal valve 
slightly convex, divided into two lobes by a deep mesial furrow extending along the middle. 
External surface not known. 
Length 4, width 4, depth 3 lines. 
Obs. Of this small species I have seen but one internal cast, which was found by the 
late Mr.Wyatt-Hdgell in the Caradoc at Tyrone, in Ireland. It somewhat resembles RA. ? 
navicula, but 1s quite distinct, and surely does not belong to the genus Phynchonella, 
where it is provisionally located. The description must necessarily be very incomplete, 
since we are not acquainted with the shell itself, or with its exterior characters ; but it was 
in all probability smooth. The original specimen forms part of the collection of the 
late Mr. Wyatt-EHdgell, and to the tablet Mr. Salter had appended the specific designation 
here reproduced. 
Genus—Hicuwaupia, Billings, 1858. 
Report of the Geological Survey of Canada for 1857, published in 1858. 
The characters appertaining to this genus have not yet been completely defined, I am 
therefore somewhat uncertain as to the place it should occupy in the classification of the 
Brachiopoda, and also whether it be really represented in our British Silurian deposits. 
Mr. Billings diagnoses his genus as follows :—“ Large valve perforated on the umbo for the 
passage of the peduncle ; the place of the foramen beneath the beak occupied by an imper- 
forate concave plate, the interior divided by an obscure medio-longitudinal ridge ; interior 
of smaller valve divided throughout from the beak to the front by a very prominent medio- 
longitudinal ridge; no hinge, teeth, sockets, or other articulating apparatus, in either 
valve.’ Mr. Billings has kindly sent me one example of his Hichwaldia subtrigonalis, as 
Iichwaldia subtrigonalis, Billings. 
