GASTEROPOD FAUNA IN THE MILLSTONE GRIT OF SCOTLAND. 351 



bounded below by an obscure ridge which continues from the umbo to the postero- 

 inferior angle. 



Interior. — Not observed. 



Exterior. — -The surface appears to be almost smooth. 



Dimensions. — Specimen No. 2441, a left valve, measures: antero-posteriorly, 

 9 mm. ; dorso-ventrally, 3 mm. (PL II. fig. 44.) 



Locality. — Dumbartonshire, Greenfoot Moulding Sand Quarry, near Gain Farm, 

 3 miles N. of Coatbridge. 



Observations. — I have referred these specimens to the genus Solenomorpha on 

 account of the elongate form and the peculiar elongated anterior end and the narrow 

 compressed umbones. The posterior end is broader than is usual in species of this 

 genus. The American Coal Measures species (Solenopsis) Solenomorpha solenoides of 

 Geinitz has the normal condition of a narrowed posterior end and a somewhat less 

 prolonged anterior end. 



Solenomya brevis, sp. nov. (PL II. figs. 45-47.) 



Specific Characters. — Shell small, transverse, tumid, lenticular, narrowed at both 

 extremities, very inequilateral. The anterior end long, its margin elliptical. The 

 inferior margin is convex ; the posterior truncate, rounded. The hinge line is gently 

 arched. The umbones are inconspicuous, elongate and adpressed, placed far back so 

 that the posterior end is short and rapidly compressed, especially above. 



Interior. — Normal. 



Exterior. — Almost smooth, with very fine concentric striae of growth. 



Dimensions. — PL II. fig. 46. Specimen No. T2718 B measures: antero-posteriorly, 

 16 mm. ; dorso-ventrally, 8 mm. ; gibbosity of valve, 3 mm. 



Locality. — Dumbartonshire, Greenfoot Moulding Sand Quarry, near Gain Farm, 

 3 miles N. of Coatbridge. 



Observations. — This species belongs to the group of Solenomya, which does not 

 possess radiating ribs passing across the middle part of the valves. The absence of 

 these ribs and the peculiar boat-shaped valve at once distinguish the species from 

 S. cylindrica, which occurs at the same horizon. Its nearest congener is S. excisa, 

 but this is a much lamer and more transverse shell. 



"o" 



Solenomya cylindrica, sp. nov. (PL II. figs. 60, 61.) 



Specific Characters. — Shell small, narrow, transversely elongate, gibbose, very 

 inequilateral. Anterior end long, its margin bluntly rounded. The hinge line and 

 inferior border are almost parallel. The posterior end narrower than the rest of the 

 valve, its margin elliptical. The umbones are small, not elevated, excavated posteriorly, 

 and placed in the posterior fourth of the hinge line. 



Interior. — Normal. 



