394 Prof. T. R. Jones on tlie 



2. Entomis depressa, Salter MS. 

 (PI. XV. figs. 2, 3.) 



Entomis depressa, Salter MS., Cat. Cambr. Silur. Foss. Mus. Pract. 

 Geol. 1878, p. 125. 



Valves nearly oval, resembling those of E. tuberosa, but 

 destitute of the large tubercle or swelling on the anterior 

 moiety, within the curvature of the sulcus, A very small 

 tubercle, however, is visible on the internal cast of each valve 

 at or near the umbilical termination of the sulcus. 



Size of valve i^X^ inch ; and ^^ x 5^0 inch. 



This form occurs in the Aymestry Limestone at Mocktree, 

 Shropshire * ; also in Upper-Ludlow mudstone at Aymestry 

 Common f. 



3. Entomis Marstoniana, sp. nov. (PI. XV. tig. 8.) 



In the Museum of Practical Geology (3^) is an interesting 

 specimen of two pairs of opened valves, each nearly semicir- 

 cular in shape, only slightly convex (on account of pressure), 

 and with a short, neatly curved, dorsal furrow. The valves 

 are quite smooth, retaining a delicate film of the decomposed 

 test, and sliowing no spot or tubercle, only a slightly raised 

 marginal rim where the edge of the valve is here and there 

 perfect. This fossil is in the bluish-grey calcareous shale of 

 the Lower-Ludlow series, from Mocktree, and was presented 

 to the museum by Mr. A. Marston, of Ludlow; and I gladly 

 associate his name with this species, for he is well known to 

 have worked hard among the fossils of the Silurian and Cam- 

 brian rocks of Shropshire, and to have added much to our 

 knowledge of the palaeontology of these old rocks. 



Size of valve if x -|-|- inch. 



Another specimen with this circular form, but not well 

 preserved, in the Museum of Practical Geology J, is from the 

 Upper-Silurian olive-brown mudstone at Ludlow. 



4. Entomis Haswelliana, sp. nov. (PI. XV. figs. 9, 10.) 



Some internal casts of small valves referable to Entomis^ 

 collected by the late Mr. G. C. Haswell about 1866 in the 

 Upper- Silurian mudstone of the Pentland Bills (probably near 

 the North-Esk reservoir), indicate a species with broadly 

 ovate valves, which are uniformly convex, though impressed 

 with a strong dorsal sulcus. This is narrow, rather sinuous, 



* Cat. Pal. Foss. Mus. Pract. Geol. 1878, p. 125 (-2/). 



t Op. cit. p. 131 (D f f). 



X Cat. Pal. Foss. 1878, p. 130 (I4). 



