242 MOLLUSCA FROM THE CRAG. 



Spec. Char. Testa ovatd subtrigonuld, subinaquilaterali, tenui, lavi, compressiusculd ; 

 ma/rgvne dorsali convexiusctdo j dentibus lateralibus remotis, Icevigatis, acutis, tenuibus ; 

 fovea cardinali magna ; sinu palliari semicirculari. 



Shell ovate, slightly trigonular, nearly equilateral, thin and smooth, somewhat 

 eompressed ; dorsal margin slightly curved ; lateral teeth remote, smooth, sharp, and 

 thin ; cartilage pit large ; palleal sinus semicircular. 



Length, 3|- inches. Height, 2| inches. 



Locality. Red Crag, Newbourn. Recent, Mediterranean, British Channel. 



This species, in the recent state, seems restricted to the warmer parts of the British 

 Seas, and to the Mediterranean, and as such we might have expected to have found it 

 in the lower Crag deposit. Two specimens were found by myself in the genuine, though 

 rather disturbed portion of the, Red Crag : there is, I think, little doubt of its having 

 been an inhabitant of the sea of this latter Period, as so large and thin a species 

 would hardly have escaped destruction in a removal from one formation to another. 

 M. stultorum is the shell with which it is most likely to be confounded ; that 

 species, however, never attains to so great a magnitude. The dental characters in 

 this are strongly marked ; the right valve has two unequal sized cardinal teeth, the 

 anterior one short, inside of which the A-formed tooth of the left valve interlocks ; 

 the lateral teeth are long, thin and sharp, rather less elevated towards the sides than 

 are those of M. stultorum, and in this species the umbo is rather more prominent : the pit 

 for the cartilage is of a triangular form, and the mantle sinus is comparatively less. 



Born seems intitled to priority, as there is very little doubt his figure, though 

 not a good one, was intended for this species, and to which Chemnitz (who has given 

 a much better representation) has referred. 



Menke has introduced this species into his ' List of New Holland Mollusca.' This 

 Australia shell may be what is called by some authors its representative. 



2. Mactra stultorum, Linnaeus. Tab. XXIII, fig. 3, a — d. 



Mactra stultorum. Gualteri. Ind. Test. Conch., t. 71, fig. c, 1742. 

 Pectunculus. Leigh. Nat. Hist. Chesh., pi. 3, fig. 6, 1700. 

 Cardium stultorum. Linn. Syst. Nat., ed. 10, p. 681, No. 8. 

 Mactra stultorum. Linn. Syst. Nat., ed. 12, p. 1126, No. 99, 1767. 



Broc. Conch. Foss. Subap., p. 535, No. 2, 1814. 



Phil. En. Moll. Sic, vol. i, p. 10, t. 3, fig. 2, 1836. 



Forb. and Hani. Hist. Brit. Moll., vol. i, p. 3G2, pi. 22, figs. 4—6. 



— cinerea. Mont. Test. Brit. Supp., p. 35, 1808. 



— magna. Woodw. Geol. of Norf., p. 43, t. 2, fig. 10, 1833. 



— straminea? Desh. 2d ed. Lamk. torn, vi, p. 100, 1835. 

 Trigonella radiata. Da Costa. Brit. Conch., p. 196, pi. 12, fig. 3, 177^- 

 Tellina radiata. Perm. Brit. Zool., ed. 4, vol. iv, p. 87, pi. 49, fig. 30. 



