BRITISH SILURIAN BRACHIOPODA. 191 



Orthis testudinaria, Bav. (not of Dalman). Sil. Mon., p. 227, pi. xxviii, figs. 

 13—24, 1868. 



Shell marginally semicircular, hinge-line a little shorter than the breadth of the shell, 

 lateral margins broadly rounded, slightly indented in front; dorsal valve moderately 

 convex and longitudinally divided into two lobes by a median depression, cardinal angles 

 either rounded or angular, slightly auriculated ; ventral valve evenly convex or with a 

 small median longitudinal elevation, beak slightly incurved, area narrow, fissure triangular. 

 Surface of both valves covered with numerous fine, thread-like radii, with one or two 

 shorter riblets interpolated between the larger rays. 

 Length 8, breadth 9 lines. 



Obs. — I believe this is the shell which has been erroneously referred to 0. testudinaria 

 by Salter in vol. 2 of the ' Memoirs of the Geological Survey,' and by myself at p. 226 of 

 the ' Silurian Monograph.' At that period neither Salter nor myself had seen Dalman's 

 types and did not understand his species. When preparing the manuscript relating to 

 the Devonian and Silurian Brachiopoda that occur in the Triassic pebble-bed of Budleigh 

 Salterton, Vol. IV, p. 329 and 358, I had some correspondence with Prof. Lindstrom 

 with respect to Dalman's species, and, with his usual amiability, he at once forwarded for 

 my inspection Dalman's own specimens and types out of the Stockholm Museum. I 

 figured the Swedish type in Vol. IV, PI. XLII, fig. 26, of my ' Monograph,' and found it 

 to be entirely different to the one figured by Salter and myself in the works already 

 alluded to. I was then and am still uncertain whether the true 0. testudi7iaria and my 

 Orthis Budleighensis may not be the same ; but, as Dr. Lindstrom seemed uncertain and 

 undecided about the matter, after having compared a number of specimens of the Budleigh 

 Salterton fossil with the Swedish form, it was determined to retain them provisionally as 

 distinct. 



Ortlds Banhini is a very much larger form than 0. testudinaria, and much more 

 transverse. Dalman's species is a small, almost circular shell, very slightly wider than 

 long, and not much exceeding some 7 lines in length by 1\ in breadth, and 3 or 3^ in 

 depth. In order to get rid of the confusion that has taken place, I have thought it 

 preferable to give to the form under description a separate designation, and have named 

 it after my valued friend the late Dr. Rankin, of Carluke, who afforded me so much 

 lielp while working out the Scottish Carboniferous Brachiopoda. 



0. Banhini was found by Mrs. R. Gray in the Llandeilo, at Ardmillan Brae, and in 

 the Star-fish Beds, or Upper Caradoc, at Thraive Dyke, in Ayrshire. It is also quoted by 

 Mr. Salter from Pont-brennaraeth, Pont Dwfn, Panblewin, Llwychgwyn, and Llandeilo. 



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