ER03I THE INFERIOR OOLITE. 515 



There is a specimen of this Gt. Oolite shell in the Bristol Museum 

 from the Inferior Oolite of Bradford Abbas, and one in the Jermyn- 

 Street Museum from the Gryphite Grit of Leckhampton. I have 

 one from the same locality. 



Plicatula Sollaslt, n. sp. Plate XY. figs. 21, 21 a, 22, 22 a, & 



22 b. 



Shell small, equilateral, transversely subtriangular or lozenge- 

 shaped, depressed, adhering by the greater part of the right valve, 

 and then suddenly rising perpendicularly, to form a rim of more 

 than a line in height, below which the adhering surface is slightly 

 expanded ; umbo indistinct and small ; margins starting from it 

 at a slight slope, curving suddenly at the shoulders (which are the 

 widest part of the shell), and then running down obliquely in almost 

 straight lines, till they meet at the centre of the lower part in a 

 strong curve ; interior with fine reticulations on the flat part, 

 formed by rounded curving lines, which branch so as to form lozenge- 

 shaped spaces. Similar, but closer markings, broken by one or two 

 transverse ridges, are continued on the inner surface of the rim ; 

 the exterior surface of which is covered by numerous, indistinct, 

 elongate striae. 



Left valve (fig. 22) with the interior slightly concave, and then 

 sinking perpendicularly to form a marginal rim two lines deep ; 

 concave part with indications of markings similar to those of the 

 other valve but much larger. On the curve of the rim are numerous 

 elongate serrations, the perpendicular side of the rim being smooth, 

 and the edge covered by fine crenulations. The exterior of this 

 valve is entirely hidden by the matrix. 



Locality. Dundry. 



Dimensions. 5 lines long, 6 wide, and 1 deep. 



I have collected many specimens of the right valve adhering to a 

 flat surface of stone, which was bored by Annelids and Litliodomi. 

 They appear very uniform in shape. I found a single left valve 

 in the upper part of the HumpJiriesianus-zonQ in the same quarry ; 

 and, though there are some differences in markings, there seems to 

 be no reason to suppose that it belongs to a different species. This 

 shell comes very near PI. reticulata of Deslongchamps (he. cit. 

 t. 18. fig. 24-35), but seems to differ in shape, and the presence of 

 markings on each surface of the rim in the right valve. PI. lepis 

 of the same author is a more elongated and rounded shell, and 

 is smooth on the interior of the rim. 



Spondylus dichotomus, Buv., differs in being orbicular as well as 

 in the absence of marking on the inner surface of the rim. 



Plicatula stjbserrata, Goldf., sp. Plate XYI. figs. 4, 5. 

 1834. Ostrea subserrata, Goldf. Petr. Germ. t. 74. fig. 1. 

 1852. Plicatula impressce, Quenst. Handb. t. 41. fig. 27. 



1857. Plicatula impressa, Oppel, Juraf. Sect. 80, no. 90. 



1858. Plicatula subserrata impresses, Quenst. Jura, t. 73. fig. 45, 46. 

 Small shells which appear to agree with this species occur in 



