234 



THE GEOLOGIST. 



XLVIII.— LiNGULA MYTiLOiDES. Sowcrbj. PL v., figs. 3843. 



Lingula mytiloides. Sowerby, "Min. Con.," tab. xix., fig. 1-2, 1813, = Lin- 

 qula elliptica and = L. parallela, Phillips' " Geology of Yorksbire," vol. ii., 

 plate xi., figs. 11-15 and 17-19, 1836. 



This shell appears to vary in shape, but is usually more or less regularly 

 elliptical or ovate, w^ith its greatest width either tovv^ards the posterior or an- 

 terior extremity. Its sides are also sometimes nearly parallel and rounded in 

 front, but both front and beaks are in other examples about equally and regu- 

 larly elliptieally attenuated. The valves are generally convex, and most 

 elevated along the middle, w^here there exists likev^^ise a flatness, which becomes 

 gradually wider as it extends from the apex of the beak to the front, the lateral 

 portions of the valves sloping rather abruptly on either side, while the surface 

 is marked at intervals by a greater or smaller number of concentric lines or 

 ridges of growth. The shell under description has been referred to Sowerby's 

 L. mytiloides, because several of the specimens were exactly similar in shape to 

 those figured by Sowerby, in 1813, and from it having appeared that L. paral- 

 lela andZ. elliptica were only slight variations in shape of the Sowerby shell (?). 

 Some palaeontologists will however, differ with me in this conclusion, and may 

 prefer retaining L. mytiloides and L. parallela as separate species, and I should 

 be glad to adopt their views if they can point out the characters by which the 

 two can be distinguished.* L. mytiloides has usually a glossy appearance, and 

 was probably when alive of a bright green colour ; it is also a common Scottish 

 species. 



In the parish of Carluke, in Lanarkshire, it occurs in the slaty ironstone, at one 

 hundred and sixty fathoms below the " Ell coal two hundred and thirty-nine 

 at Gare ; three hundred at Mashock Burn ; three hundred and thirty-seven at 

 Haes Gill, Braidwood, and Langshaw Burn, etc. ; three hundred and seventy- 

 one at Kilcadzow. It occurs likewise at Hall HiU, near Lesmahago ; Capel 

 Rig, East Kilbride; Calderside and Auchentibber, High Blantyre; Bishop- 

 briggs and Bobroyston, north of Glasgow. In Renfrewshire, at Orchard- 

 quarry, Thornliebank. In Ayrshire, at West Broadstone, Beith. In Stirling- 

 shire, at Craigenglen, and Corrie Burn. In Eifeshire, at Craig Hartle, etc. It 

 has also been found along the Berwickshire coast : and at Marshall Meadows, 

 three miles north of Berwick, a very elongated variety has been discovered by 

 Mr. Tate, and for which he proposes the designation of L. elongata. 



XLIX. — SpiEirERiNA LAMiNOSA. M'Coy. PL v., figs. 8-9. 



Cyrtia laminosa. M'Coy, " Synopsis of the Carb. Eossils of Ireland, p. 137, 

 pi. xxi., fig. 4, 1814. Spirifera id., "Dav. Br. Carb. Men., pi. vii., figs. 17-22. 



This form is generally sub-rhomboidal, with convex valves, the lateral por- 

 tions of the shell being regularly curved, vdth acute cardinal extremities : the 

 hinge-line is as long as the greatest width of the shell. The area large, tri- 

 angular, and divided by a fissure of moderate width. The beak is small, and 

 not much produced above or beyond the level of the area. The mesial fold in 

 the dorsal valve is broad, more or less elevated, and without ribs, while the 

 sinus in the ventral valve is wide, and of moderate depth ; there exists also on 

 the lateral portions of each valve from sixteen to twenty narrow radiating ribs, 

 intersected by closely disposed, sharp, concentric, undulating laminae. 



This species evidently exists in Scotland, although no perfect example with 



* AtpagG 368 of his History of British Animals," while describing Lingula mytiloides. Dr. 

 Fleming? refers to Ure's plate xvi., fig. 5, as probably belonging to the species in question, but 

 1 am convinced that tliis is a mistake, as the shell there represented is fai' from resembling 

 any Lingula -N^-ith which I am acquainted. 



