350 DR WHEELTON HIND ON THE LAMELLIBRANCH AND 



angle of the valve extends a blunt subangular ridge, which divides the convex portion 

 of the valve from the concavity of the dorsal slope. 



Interior. — Not known. 



Exterior. — The surface of the valve is ornamented with numerous concentric, 

 irregular rugae and lines of growth, which tend to become obsolete on the dorsal slope. 



Dimensions. — Specimen No. T2450 B measures: antero-posteriorly, 11 mm.; dorso- 

 ventrally, 7 mm. ; gibbosity of valve, 3 mm. 



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

 3 miles N. of Coatbridge ; Stirlingshire, Torwood Glen, 1\ miles N.W. of Larbert, 9 to 

 10 feet above the Castlecary Limestone; Linlithgow, river Avon, 35 to 40 feet above 

 the Castlecary Limestone. 



Observations. — This species is represented in the collection by a very large number 

 of individuals, by far the largest number of which came from the Gain Quarry. The 

 specimens occur in ferruginous nodules which lie above the Upper Cementstone. The 

 shell has a distinctive appearance, being very rugose for so small a shell. The narrowed 

 truncate posterior end and well-compressed dorsal slope, comparatively large lunule and 

 escutcheon, indicate fairly conclusively, even in the absence of details of the hinge and 

 interior, the generic affinity of the species. The genus Tellinomya is represented in 

 the Coal Measures of North America by Tellinomya [Allorisma, Sedgivickia) granosa 

 of Shumard, and probably the Allorisma [Sedgivickia) subelegans of Meek. The 

 former species is very much larger than the one just described, but the latter agrees 

 with it very well as to size. From the figure and descriptions, the ornament appears 

 to be regular, and the shell is described by Meek as rather compressed, a character 

 which does not suit the Scotch species. With a strong lens, I think the remains of 

 the characteristic tubercles with which the surface of shells belonging to the genus are 

 covered are to be seen. Since writing the description I recognised the species in a 

 collection made by Mr H. Bolton from the base of the Coal Measures of Bristol, who 

 has published a description and figures {pp. supra cit.). He appears doubtful of the 

 genus, and suggests Parallelodon, but I cannot accept this view. The small amount 

 of the hinge plate that I have seen has none of the characters of that genus. The 

 antero-superior angle of the shell is quite unlike the arciform type, and is rounded, and 

 not square and compressed. 



Solenomorpha cylindrica, sp. nov. (PL II. figs. 43, 44.) 



Specific Characters. — Shell small, narrow, transverse, very inequilateral, dorsal and 

 ventral margins subparallel. The anterior end is comparatively elongate, narrow ; its 

 anterior superior angle almost pointed, the border elliptically curved. The posterior 

 end is truncate, blunt, not much narrowed, making a rounded angle below with the 

 inferior margin, and a slightly obtuse angle with the hinge line above. The umbones 

 are compressed, elongate, and not elevated. The dorsal slope is slightly compressed, 



