GASTEROPOD FAUNA IN THE MILLSTONE GRIT OF SCOTLAND. 353 



Prothyris elegans, Meek, 1871. (PL II. figs. 48-50.) 



Prothyris elegans, Meek, 1871, Ajner. Journ. Conch., vol. vii. p. 5, pi. i. fig. 3. 



,, ,, Meek and Hayden, 1872, Fin. Rep. U.S. Geol. Surv. Nebraska, p. 223, 



pi. x. fig. 9, a, b. 



Specific Characters. — Shell moderately compressed, transversely oblong, dorsal and 

 ventral margins straight and parallel. The anterior superior angle is expanded into a 

 small, pear-shaped process, not extending below the upper third of the border, the 

 broad end pointing downwards and forwards. This process is separated from the rest 

 of the shell by a raised ridge, which is continued below as the anterior margin, which is 

 bluntly rounded. The posterior margin is obliquely subtruncate and almost straight. 

 The postero- inferior angle bluntly rounded ; the postero-superior angle almost obtuse. 

 The umbones very small, depressed, and placed very far forwards : they would be 

 terminal were it not for the ear-like expansion. The upper margin of each valve is 

 compressed by a shallow groove immediately below the hinge line. Another groove 

 passes obliquely from the region of the umbo towards the posterior margin some little 

 distance below. Below these two grooves is a rounded ridge, which becomes broader 

 as it approaches the posterior end. Below this the valve is very gently convex. 



Interior. — Unknown. 



Exterior. — That portion of the valve near the upper margin and the dorsal slope is 

 almost smooth. Nearer the ventral border there are fine close lines of growth, parallel 

 with the margins. 



Dimensions. — PI. II. fig. 48. Specimen No. T2505 B , a right valve, measures : 

 antero-posteriorly, 17 mm. ; dorso-ventrally, 5 mm. 



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

 3 miles N. of Coatbridge. Horizon : Millstone Grit of Scotland. 



Observations. — Although the Rev. G. F. Whidborne has recorded three species of 

 the genus Prothyris from the Devonian rocks of England, it has not been previously 

 found in the Carboniferous beds of Great Britain [vide ante, p. 332). The type of the 

 genus is Prothyris elegans, a species which occurs in the Coal Measures of Nebraska 

 and Illinois. I have been unable to note any specific difference between the American 

 and Scotch specimens after careful comparison with a series from Nebraska in my 

 collection. Many examples have been obtained by Mr. Tait from the locality named 

 above — fortunately right and left valves. In some the ear-like process which is 

 characteristic of the genus has broken away. The left valve is represented by the 

 fossil and its counterpart, the latter showing the ear very perfectly. I have seen other 

 examples in the possession of Mr. J. Smith of Dairy. 



Gasteropoda. 



Loxonema nanum, de Koninck, 1881. (PL II. fig. 51.) 

 Loxonema nanum, de Koninck, 1881, Ann. Mils. Roy. d'Hist. Belg., tome vi. p. 50, pi. iv. figs. 45, 46. 

 Specific Characters. — Shell very small, elongate ; spire consisting of 8 to 9 whorls. 



