BIVALVIA. 87 



This very common Inferior Oolite species occurs rarely in the Great Oolite, but it is 

 absent in the shelly beds of the formation in Gloucestershire. 



Geological position and localities. Minchinhampton and Scarborough in the Great 

 Oolite ; the Cotteswolds, Dundry, Yeovil, and Brora in the Inferior Oolite ; Malton in 

 the Coralline Oolite. 



ASTARTE INTERLINEATA., VttT. LyC., Sp. Tab. IX, fig. 14, 15fl, 6. 



HIATELLA ? INTERLINEATA, Lycett. Anu. and Mag. Nat. Hist., 1850, p. 421. 



Testa pared subquadratd vel oblongd, convexo-pland ; umbonibm acutis, parvis, ante- 

 medianis; lunuld excavatd; margins superiori et inferiori parallelis subrectis, antico 

 rotunda, postico truncato , angulo obliquo; costis longitudinalibm magnis, postice in 

 angulo flectis et trinodulosis ; striis interstitialibus tenuissimis instructis. 



Shell small, subquadrate or oblong, slightly convex ; umbones acute, small, depressed, 

 and placed anterior to the middle of the valves ; lunule excavated ; superior and inferior 

 margins parallel, horizontal, and straight ; anterior border rounded ; posterior border 

 truncated ; longitudinal costse few, somewhat irregular, large, and rounded in the Great 

 Oolite variety, bent posteriorly upwards, forming an acute angle ; their posterior portions 

 have also in this variety three rather obscure nodules ; the interstitial spaces have very fine 

 longitudinal striations. 



This species presents itself under two varieties of aspect, one of which occurs in the 

 middle portion of the Cotteswold Inferior Oolite. This latter and more smooth variety 

 has the figure somewhat shorter, the costae rather more distant ; they are also more narrow 

 and acute ; and posteriorly they have not the nodules of the other variety. It must not, 

 however, be inferred that these distinctions are preserved in all specimens ; on the contrary, 

 the posterior nodules are uncertain in their distinctness ; the number of costa? and their 

 size are equally variable. The test is delicate. 



Height, 3 lines ; length, 4i lines ; diameter through both the valves, 2 lines : but the 

 greater number of specimens have smaller dimensions. . 



Geological position and localities. Astarte interlineata occurs in the shelly freestone of 

 the Inferior Oolite of Leckhampton and of the Minchinhampton, and likewise in the shelly 

 Great Oolite of the latter locality. 



ASTARTE WILTONI. Tab. IX, fig. 16. 



Testa ovato-subangulari planatd, umbonibus anticis acutis ; costis apicialibus concentricis 

 paucis, magnis. 



Shell ovately subangular or subquadrate, flattened ; umbones anterior, acute ; the 

 surface with a few acute concentric costae near to the apex ; the other portion of the 

 surface nearly smooth. 



