280 CARBONIFEROUS LAMELL1BRANCHIATA. 



As both specimens are crushed, it is impossible to obtain an idea of the con- 

 vexity of the valves. 



Localities. — Scotland : Limestone No. 6, Randerstone, Fife, Calciferous 

 Sandstone series ; and Magazine, Midlothian, Carboniferous Limestone series. 

 Ireland : Carrowmacrory, Templeboy ; and in arenaceous shale, Rahan's Bay, 

 Dunkinealy. 



Observations. — The type specimen is very imperfect and much crushed, as are 

 also all the specimens I have been able to examine from Randerstone, but there 

 can be little doubt that M'Coy's species was well established. I have fortunately 

 procured a fine cast of the interior of a pair of valves from Magazine, PI. XXVI, 

 fig. 3, which enables me to give details of the interior, and also gives a good idea 

 of the shape of the shell. The hinge is represented in this specimen by a 

 hollow groove, showing that M'Coy was correct in asserting that certain species 

 of this genus were edentulous. 



Mr. Kirkby, referring to the Randerstone shells, says (op. supra cit.), " I 

 have several specimens of a large Schizodus-sh&ped shell from Limestone No. 6, 

 Randerstone, which evidently came very close to the SedgwicJeia gigantea, M'Coy. 

 The specimens which are all more or less crushed are thin -shelled, from three to 

 three and a quarter inches long, two inches wide, and have the anterior side 

 marked with the regular strong ridges parallel with the margin that are charac- 

 teristic of the genus, the remainder of the surface being comparatively smooth." 

 I think there is no doubt that this reference is correct, for although much larger, 

 as far as may be judged from their crushed condition, they are identical in 

 character with the type. 



It would appear that M'Coy's figure of 8. gigantea is largely ideal ; the type 

 specimen preserved in the Griffith Collection of the Royal Museum of Science and 

 Art, Dublin, is very much crushed and imperfect. I have been kindly permitted 

 by the authorities to re-figure this specimen, PI. XXVI, fig. 1. 



I have placed the Dolabra securiformis, M'Coy, as a synonym of 8. gigantea, of 

 which it is an internal cast, and its figure, PL XXVII, fig. 10, is seen to be 

 identical with the very perfect specimen from Magazine, near Edinburgh, which is 

 represented on PI. XXVI, fig. 3. The casts of 8. gigantea do not exhibit any 

 marked traces of the peculiar external ornament, and are therefore somewhat 

 difficult to separate from specimens of Protoschizodus in a similar state of 

 preservation, especially if no trace of the hinge of the latter genus be visible. 



