RHYNCHONELLID A. 199 
Penwhapple Bridge on the Barr road, three miles and a half from Old Daily church, 
Girvan, Ayrshire. 
In England it was found by Mr. Lightbody in the Caradoc of Llandeilo (Birds Hill) ; 
and in the Museum of Practical Geology of London may be seen specimens from Pistyll 
Deroi, Llandeilo. I am not acquainted with the shell from any other locality or country. 
Although the foregoing is the only British Silurian species which is, perhaps, properly 
located in the genus Z)iplesia, I have provisionally ventured to add those that now follow, 
not knowing to what other genus they can be allotted. 
Triptesia ? Maccoyana, sp. nov. Pl. XXIV, fig. 29. 
HeMITHyRIS DEPRESSA, M‘Coy. Brit. Pal. Foss., p. 201, 1852 (not Alrypa depressa, 
Sow.). 
Spec. Char. Shell small, transversely oval, greatest breadth at about the middle ; 
ventral valve slightly convex at its rostral portion, depressed towards the lateral margins, 
while a triangular sinus of moderate depth commences at a short distance from the ex- 
tremity of the beak and extends to the front. Hinge-line short, area triangular and 
narrow, a small aperture existing under its small, prominent, pointed beak. Dorsal 
valve convex, sometimes much so, and strongly arched when viewed in profile. Mesial 
fold rising gradually, and chiefly confined to the anterior half of the shell. Surfaces 
of both valves smooth or marked by concentric lines of growth. 
Length 5, width 53, depth 3 lines. 
Obs. My attention was first drawn to this shell by Mr. Salter while on a visit to 
Cambridge. That experienced paleontologist at once perceived that it was not the 
Atrypa depressa of Sowerby, as erroneously supposed and described by M‘Coy, but 
that it was, perhaps, a new species of Zriplesia. I regret, however, that from want of time 
(while in Cambridge) I was not able to study the shell as carefully as I desired, but 
I clearly saw the small area which exists between the extremity of the beak and hinge- 
line, but of which no mention is made by M‘Coy. Eight specimens from the Bala Lime- 
stone of Brynbedwog Quarry, near Bala, Merionethshire, are preserved in the Woodwardian 
Museum. This Brachiopod is here provisionally classed with Zriplesia, as it is the genus 
to which it appears to bear most resemblance. I have also named it after Prof. M‘Coy, 
to whom science is indebted for many excellent works. 
