APPENDIX. 325 



MACTRA TRIANGULATA, S. Wood. Tab. XXXI, fig. 21 a d. 



Spec. Char. Testa parvd, ovato-triangulatd, utroque obtusissime carinatd, crassd, striatd out 

 sulcatd ; dentibus lateralibus magnis, perpendicularibus striatis. 



Shell small, ovately and broadly triangular; both sides obtusely keeled, thick, striated, or rather 

 sulcated ; lateral teeth large, perpendicularly striated. 



Length, f inch. 



Locality. Cor. Crag, Sutton. 



Small specimens of this species are abundant, but they are always more or less decorticated, and, as the 

 principal distinction is in the sculpture, they have until now remained in my cabinet as varieties of M. ovata. 

 Two or three individuals have recently been obtained with a sufficiency of the outer surface to show that a 

 difference existed between it and the recent shell, M. ovata (M. elliptica, F. and H.), such as, I now believe, 

 will entitle this to a separate specific position : instead of being covered with numerous, fine, irregular, and 

 sometimes inosculating striae, like those upon the recent British shell, our fossil is ornamented with regular 

 and distinct ridges, and deep sulci between them, corresponding in that character with Brocchi's description 

 of M.triangula, Renieri, "transversim sulcata ;" but Messrs. Forbes and Hanley have determined the 

 triangula, Phil., (M. lactea, Poli, which I presume to be the same,) to belong to M. subtruncata, Mont. 

 With these discrepancies, and not having been able to see the Subapennine fossil, the above name is given 

 provisionally until it can be better determined. 



LUTRARIA RUGOSA, Chemnitz. Tab. XXXI, fig. 26 a, b. 



MACTRA RUGOSA. Chemn. Conch. Cab., vol. vi, p. 236, t. 24, fig. 236, 1782. 

 LUTRARIA RUGOSA. Lamk. Hist, des An. s. Vert., torn, v, p. 469. 



Desh. Trait. Elem. Conch., t. 10, fig. 7. 



Sismonda. Syn. Meth. Fed. Foss., p. 23, 1847. 



Dixon. Geol. of Sussex, p. 17, 1850. 



Ency. Method., pi. 254, fig. 2 a, b. 



Spec. Char. " Testd ovato-oblongd, longitudinaliter dense striatd, et quasi costatd ; area anticd et 

 posticd glabratd, obsolete transversim striatd; margine exteriore crenulato ; colore extus ex albido Jlaves- 

 cente, intus calcareo." Chemn. 



Shell ovately oblong, striated and costated ; anterior and posterior areas generally smooth ; lines of 

 growth visible ; outer margin crenulated or wavy. 



Diameter, 2 inches. 



Locality. Bracklesham. Recent, Coast of Portugal and Mediterranean. 



This species, as a British fossil, appears to be confined to the above locality, where, I believe, it is not 

 very abundant. This, like Pecten polymorphus, is no longer an inhabitant of our own shores. It is said 

 to be found fossil at Astigiani. The specimen figured is in the museum in Jermyn Street. 



Lutraria solenoides (oblonaa) is enumerated in Mr. Dixon's 'List of Upper Tertiary Fossils at 

 Bracklesham.' 



