PORTLAND EOCKS OF ENGLAND. 233 



Height f the length. Posterior side truncate, with an angular 

 margin. N"© ribs seen on the truncated portion ; the rest of the 

 surface has fine concentric lines. It is not certain that this is a 

 Cardium ; but it only differs from C. Dafrenoycum in appearance 

 by being broader and wanting the radiating ribs on the truncated 

 part. 



It is rather widely distributed, and is best preserved in the chalk 

 of Chicksgrove. 



Teigonia savindonensis, spec. nov. PI. X. fig. 4. 



Breadth | the length, united thickness f the length. The um- 

 bones situated very near the anterior border, not very prominent ; 

 the anterior border is only slightly convex, and rounds off rapidly, 

 with a marked change of curvature into the pallial border, which is 

 gently and uniformly rounded ; posterior border rounded, passing 

 into the pallial border. The posterior hinge-line is only slightly 

 concave, and slopes but slightly, making the whole figure a rounded 

 trapezoid. Escutcheon moderately narrow, concave, with its upper 

 border raised ; only lines of growth on its surface. Area narrow, by 

 degrees becoming very slightly different in direction from the lateral 

 portion of the shell. It is subdivided by a groove bounded below by 

 very small tubercles. The area is bounded by two other rows, the 

 lower set the larger. Lateral portions have the tuberculated costa3 

 separated from the area by a very shallow depression ; ribs not more 

 than twelve in number, at first pointing posteriorly, and then making 

 a rapid bend to the anterior side ; the tubercles arc compressed and 

 strongest at the bend, dying oft' as usual anteriorly ; lines of growth 

 well marked. The elongated form permits only of comparison with 

 T. Pellati, T. muricata^ and T. incurva. Erom the first it differs by 

 the direction of the ribs and its tubercled border of the area, from 

 the second by the fewness of its ribs and the details of the area, and 

 from the last by its oblong shape and regularity of ribs, though the 

 specimen figured by Dr. Lycett in ' The fossil Trigonioe,' pi. ix. 

 fig. 4, under the latter name may very likely belongs to this. 



In the Swindon Sands, west of Swindon. 



Leda, sp. PL IX. fig. 16. 



A small example, looking as if it belonged to this genus, is figured 

 from the freestones of Swindon ; it may nevertheless be the Corbula 

 Bayani of De Loriol. 



Plicatula EcniNoiDEs, spec. nov. PI. X. fig. 6. 



General axis oblique. Upper valve slightly convex, most so at 

 the apex, where the valves were adherent ; four or five irregular 

 lost ribs, rising to spines which are not prolonged into tubes ; these 

 ribs bifurcate, or are only marked by the spines ; there are fine 

 intermed." te elevations, but no stria); the lines of growth are con- 

 spicuous. Under valve undulating ; spines, which are tubular, not 

 confined to the elevations ; the whole surface covered with radiating 

 rounded riblets. This is very nearly allied to P. echinus, Deslong- 



Q. J. G. S. No. 142. R 



