RHYNCHONELLIDA. 189 
‘Catalogue of the Fossils in the Museum of Practical Geology,’ published in 1865, 
other localities are recorded, as follow :—Craig Head, Girvan; Cerrig-y-Druidion ; 
Desertcreight, ‘Tyrone; and Harnage Park, Cressage; all in the Caradoc or Bala 
formation. 
RuyYNcHONELLA ? Benriana, sp. nov. Pl. XXIV, fig. 22. 
Spec. Char. Almost circular, nearly as wide as long. Dorsal valve convex; mesial 
fold wide, more or less elevated and flattened along the middle ; commencing at the frontal 
margin, it extends to rather more than half the length of the valve. Ventral valve convex, 
but much less deep than the opposite one; sinus concave, of greater or lesser depth, 
forming in front a convex curve or wave rising abruptly on either of the lateral sides ; beak 
small, closely incurved. Surface smooth. 
Length 5, width 6, depth 4 lines. 
Some examples, however, attained nearly the double of the above dimensions. 
Obs. When quite young the shell is much flattened or very slightly convex, with 
hardly any definable fold and sinus; these, however, become developed with age, as seen 
in the figure. In external shape it somewhat resembles one or two Bohemian Silurian 
forms figured by Barrande ; but from these our shell differs in several details. I name it 
after Mr. Thomas Belt, to whom science is indebted for valuable researches among the Lower 
Silurian and Cambrian rocks. 
Position and Locality. Rh. Beltiana occurs in rocks of Wenlock or of May Hill age, 
at Cahireconree, County Kerry, Ireland ; and a fine series of specimens may be seen in the 
Museum of the Geological Survey of Ireland. 
RuyNcwonewa ? Portiockrana, sp. nov. Pl. XXIV, figs. 23—25. 
Spec. Char. Ovate, or nearly circular, usually longer than wide. Dorsal valve 
convex, divided into three longitudinal convex lobes, of which the central one forms the 
mesial fold; it is narrow at its commencement close to the umbone, and continues so 
for some distance, but afterwards gradually increases in width and elevation as it nears the 
front. Ventral valve convex, and deeper than the opposite one ; sinus concave, turning in 
abruptly on either side ; beak small, incurved. Surface smooth, feebly marked by concentric 
lines of growth. ‘Two specimens measured— 
Length 3, width 23, depth 2 lines. 
cease, ante Peale ere 
Obs. ‘This small shell is remarkable on account of the trilobed shape of its ventral 
valve, as well as from the form of its mesial fold. This last feature easily distinguishes it 
from the larger 2A. ? Beltiana. When quite young the dorsal valve is almost flat, the 
