86 CRETACEOUS LAMELLIBRANCHIA. 



Surface of valves smooth except for growth-ridges, of which the curved portions 

 near the dorsal margin are more distinct than the other portions. 



Hinge with small transverse teeth at the anterior end and six or seven long 

 narrow oblique teeth near the posterior end — the latter decreasing in length 

 posteriorly. 



Measurements .- 



(i) (2) (3) (4) 



Height 1 . 31 . 24 . 15 . 8 mm. 

 Length 2 .182 .125 . 74 . 35 „ 

 (1—4) Gault, Folkestone. 



Affinities. — This species belongs to Freeh's 3 ' Group of Gervillia solenoides.' 



The only localities given for G. Forbesiana by d'Orbigny are Shanklin and 

 Atherfield, and apparently his figured specimen came from the latter place. All 

 the examples from Shanklin are in the form of casts of which the posterior part is 

 usually missing ; it is consequently difficult to make out their real characters, but 

 they probably belong to this species. 



The examples found in the Gault and Upper Greensand differ somewhat from 

 the specimen figured by d'Orbigny. In the former the shell is less slender and 

 tapers more quickly posteriorly ; the posterior ear, however, agrees with d'Orbigny 's 

 figure. 



A considerable number of examples of Gervillia from different localities and 

 horizons have been referred by various writers 4 to G. solenoides, Defrance, 5 but 

 without seeing a large collection of those forms it is impossible to determine their 

 relationship to one another and to the examples here described. The figures given 

 by Defrance do not enable us to form a satisfactory idea of the characters of the 

 species ; in his original account (1820) he gave " He d'Aix " as the locality, but in 

 his later remarks (1824) he states that the specimens came from the department 

 of Le Manche. 



The Senonian specimens figured by d'Orbigny 6 as G. aviculoides (non G. 



1 From posterior end of hinge-line to opposite margin of valve. 



2 From umbo to posterior extremity. 



:5 'Centralb. fur Min.,' etc. (1902), p. 615. 



4 Sowerby (1826), Goldfuss (1836), Eeuss (1846), Miiller (1847), d'Orbigny (1847), Alth (1850), 

 Zittel (1866), Favre (1869), Stoliczka (1871), Geinitz (1873), Brauns (1876), Fritscli (1877-93), 

 Notling (1885), Griepenkerl (1889), Holzapfel (1889), Liindgren (1894), Vogel (1895), Muller (1898), 

 G. oblonga, Bohm (1885). 



■> 'Diet. Sci. nat.,' vol. xviii (1820), p. 503; vol. xxxii (1824), p. 316, pi. lxxxvi, fig. 6. 



e 'Pal. Franc. Terr. Oct.,' vol. iii (1846), p. 489, pi. cccxcvii, fig. 2 (and perhaps fig. 1). Prof. 

 M. Boule informs me that the original of fig. 1 cannot be found in the d'Orbigny collection, and that 

 the original of fig. 2 comes from Valognes (Manche). 



