214 Prof. T. R. Jones and Dr. H. B. Holl on 



1. Tlili]}sura corpuUnta, sp. nov. PL XV. figs. 1 a, Z*, c, d. 



Carapace short, thick, and liigh ; ovate in side view, nearly 

 oblong in profile, and subquadrate in end view. Valves nar- 

 rowing and compressed at the anterior edge ; convex behind, 

 but pinched-in suddenly with an obliquely longitudinal median 

 sulcus (nearly half the length of the valve), and ending with 

 a thick projecting posterior lij) or rim. This conformation of 

 the posterior third of the carapace sometimes gives its ventral 

 profile (fig. 1 h) a tripartite aspect, when the marginal rim is 

 strong and distinct from the convexity on each side. The end 

 view also is peculiar (fig. Id)^ on account of the lateral im- 

 press of the furrow on either valve. This caudal notch is 

 liable to some variation, being either broad or narrow, with 

 either straight or curved edges, which are more sharply de- 

 fined in some specimens than in others. In one of the large 

 specimens from the Woolhope series we have seen a small, 

 shallow, pear-shaped depression a little in advance of and be- 

 low the centre of the valve ; and there is, in an individual of 

 medium size from the Wenlock beds, an anterior notch, short 

 and obliquely transverse, just in front of the centre of the 

 valve. Tlilq)sura corjndenta varies as to the relative propor- 

 tions both of the carapace and its pits and notches. 



Several large specimens have been obtained from the calca- 

 reous bands at the base of the Woolhope series, near Malvern, 

 where it is not uncommon. Dr. Grindrod has collected this 

 species in the Woolhope Shales of West Malvern (laminated 

 mudstones full of Polyzoa and small Brachiopods) , in which it 

 is rather common. It is common also in the lower beds of 

 the Wenlock Shale, and less frequent in the Wenlock Lime- 

 stone. 



2. Thli2}snra tuherosa, sp. nov. PI. XV. figs. 2 a, h, c. 



This is nearly related to T/i. corj^ulenta, but is more oval 

 than ovate in outline, less oblong in profile, and is characterized 

 by a somewhat compressed ventral margin, and by a promi- 

 nent boss, on each valve, defined by two slight j^arallel trans- 

 verse sulci, rather in advance of the middle of the valve. The 

 sides of the caudal furrow are rather more elevated, as distinct 

 though faint ridges, than is shown in our figure. 



Tills specimen (unique) is from the base of the Wenlock 

 Shale, Elton Lane, near Ludlow. The shell has been dis- 

 solved away in its matrix to a thin film, and broken through 

 at the central eminences. 



3. TMij)sura V-scri^yta, sp. nov. PL XV. figs. 3 a, b, c. 

 This also is related to Th. corprdcnta^ but it is much smaller. 



