FEOH THE INEEBIOE OOLITE. 519 



Inferior Oolite of • Stubbington, and in the British Museum one 

 from the Barnack Eag. 



It is quite unlike Mytilus lunularis, Lycett, ' Cotteswold Hills,' 

 p. 128, which has a sharp concave ridge overhanging the whole 

 anterior side to the inferior margin : neither do I think it agrees 

 with Mytilus Leckenbyi, Morr. and Lye, pt. ii. 1. 14. fig. 9, on account 

 of its larger anterior wing and more angulated posterior margin, or 

 with Mytilus Binfieldi, Morr. and Lye, pt. ii. t. 4. fig. 10, on account 

 of the more twisted nature of its surface. M. sublcevis, Sow., as 

 figured by Morris and Lycett, pt. ii. t. 4. fig.19, is more arched in 

 front and flatter behind, and M. ungulatus, Young and Bird = M. 

 tumidus, Morr. and Lye, loc. cit. fig. 6, is more tumid, and has a 

 larger anterior wing. 



Mytilus steiatissimes, n. sp. Plate XVI. fig. 12. 



Shell elongated, oblique, arched or laterally ungulate, sometimes 

 rather squared behind ; very convex in front, but flattened towards 

 the inferior margin. Umbones terminal, acute, elongated, and 

 curved forward, depressed and attenuated at the apex. Lines of 

 growth distant and well marked, becoming closer and sharp near 

 the margins. Radiations very fine and extremely numerous, close, 

 rounded, and smooth, except that they are rendered somewhat rugose 

 or zigzag by the crossing of the lines of growth, but not ornamented 

 by transverse markings, very regularly radiating and, occasionally, 

 dichotomizing, so as to remain the same size on all parts of the shell. 

 Anterior ear very small and steep, having a small portion of the 

 surface smooth and without rays on its hinder part. Hinge-line 

 straight and of considerable length. Anterior margin concave ; pos- 

 terior convex ; inferior ovate. 



Dimensions. 2| inches long by 1-^- wide by 2| deep for both valves 

 (Bristol Museum). 



There are two specimens in the Bristol Museum from Hundry : 

 two in the British Museum labelled " LecKhampton" (though having 

 much the appearance of Dundry fossils), and a smaller one in the 

 Jermyn- Street Museum from Castle Cary, near Bruton. 



This shell is distinct from Mytilus furcatus, as figured by Goldfuss, 

 by Quenstedt, and by Morris and Lycett. In all of these the ribs 

 are much larger, fewer, and highly ornamented. 



Modiola aspera, Sow., differs by having imbricated and fewer ribs, 

 and a much more elongated anterior wing. It is still more unlike 

 Phillips's figure of this shell, which Lycett supposes to represent M. 

 furcatus, and which D'Orbigny has referred to a distinct species 

 under the dreadful name of " subasperus" 



It more nearly approaches Mytilus pectinatus, Sow., Min. Conch, 

 t. 282 ; but in this Corallian fossil, the rays seem to be very much 

 finer, and the anterior wing still smaller and without any smooth 

 surface ; while it is a much straighter and more wedge-like shell. 

 This was quoted by Lycett, in the ' Annals,' 1850, from the Inferior 

 Oolite and Great Oolite of Gloucestershire ; but it is not mentioned 

 in his monograph, which was published soon afterwards. 



Q.J.G.S. No. 156. 2p 



