SILURIAN MOLLUSCA. 187 



In t. 20. f. 1. of the ' Silurian System/ Mr. Sowerby seems 

 to have united two distinct fossils (the differences between which 

 have been noticed by various writers) under the one name. Area 

 Eastnori ; the fig. 1 a. from Eastnor Park should, from the name, 

 be considered the type of the species, and is a regular, subcom- 

 pressed, oval shell without ventral sinus, while the other, fig. 1 b, 

 — of which Mr. Sowerby says, " If it be not an old shell grown 

 very thick, it may be a different species," — may I think possibly 

 be referred to the present fossil. 



In the gray micaceous sandstone of Llechclawdd, Myddfai. 



(Col. University of Cambridge.) 



Area Edmondiiformis (M^Coy). 



Sp. Char. Oblong, obtusely subquadrate, very gibbous; beaks 

 very large, tumid, about one-fourth of the length from the 

 anterior end, which is obtusely rounded ; ventral margin 

 slightly sinuate in the middle ; posterior end very slightly ob- 

 lique, obtusely rounded ; hinge-line nearly straight, as long as 

 the shell, with numerous minute teeth inclining slightly to- 

 wards the beak ; surface smooth or with minute wrinkles of 

 growth. Width 5 lines, length 7g- lines, greatest depth of one 

 valve (at middle) 2i lines. 



This ^species resembles a small Modiolopsis or Edmondia in 

 form, but in some of the specimens the hinge-teeth are seen as 

 in Area, except that they incline slightly towards the beak in- 

 stead of from it. 



In the fine sandy beds near Llangynyw Rectory, Montgo- 

 meryshire ; sandstone of Alt y Gader ; in the Upper Ludlow 

 Rock of Benson Knot, Kendal, Westmoreland; Moel Seisiog, 

 Llanrwst ; Bala, Merionethshire ; and Ab Hirnant. 



[Col. University of Cambridge.) 



Dolabra elliptica (M^Coy). 



Sp. Char. Elongate, elliptical, length slightly more than twice 

 the width ; beaks obtuse, moderate, one-sixth of the length 

 from the anterior end ; anterior end small, elliptically rounded ; 

 ventral margin slightly convex ; hinge-line slightly elevated ; 

 posterior end obliquely rounded ; valves moderately convex ; 

 diagonal ridge very obtusely rounded, posterior slope steep, 

 but not abruptly flattened ; surface apparently marked with 

 fine lines of growth. Length 1 inch 6 lines, width from beak 

 to opposite margin 8 lines, width from ventral margin to end 

 of hinge-line about the same, depth of one valve 3 lines. 



The specimen described shows that in the left valve there were 

 no other teeth but the thick elongat^c posterior one or ligamen- 



