78. MOLLUSCA FROM THE CRAG. 
Arca Garmarpit. Desh. Exp. Sci. Algiers Moll., pl. 124, figs. 8—11. 
— Qvoyi. Payr. Cat. Moll. Cors., p. 62, pl. 1, figs. 40—43, 1826. 
a — Desh. Append. to Lyell’s Princ., Ist ed., vol. ii, p. 10, 1833. 
— uactanza. S. Wood. Mag. Nat. Hist., New Series, vol. iv, p. 232, pl. 13, fig. 3, 
1840. 3 
— — S. Wood. Catalogue, 1840. 
— — Morris. Cat. Brit. Foss., p. 78, 1843. 
— wnopuLosa? Broce. Conch. Foss. Subap., p. 478, t. ii, fig. 6, a—e, 1814. 
— — ? Dubois. Wolhyn. Podol., p. 64, pl. 7, figs. 21, 22, 1831. 
— striata. Reeve. Conch. Icon. Arca, pl. 17, fig. 121. 
List. Hist. Conch., lib. iii, fig. 69, 1685. 
Dale. Hist. and Antiq. of Harwich, p. 291, 1730. 
Adanson. Voy. au Senegal, p. 250, pl. 18, fig. 8, 1757. 
not Arca LacTEA, Brander. Foss. Hant., pl. 8, fig. 106. 
Spec. Char. Testa ovato-oblongd, interdum subquadratd, anticé rotundatd, posticé 
oblique truncata ; decussato-striatd ; striis radiantibus eminentioribus ; area cardinali 
mediocre profunda ; margine ventrali subrecta. 
Shell ovato-oblong, sometimes nearly square, anterior side rounded; posterior 
obliquely truncated; covered with striz, crossed by transverse lines of growth; 
radiating striz the most prominent; cardinal area not large, with a rounded or obtuse 
ridge from the umbo backwards; ventral margin nearly straight. 
Longest diameter, = of an inch; height, 5 an inch. 
Locality. Cor. Crag, Sutton. 
Red Crag, Sutton, Walton Naze. Recent, Britain and Mediterranean. 
In the sandy portion of the Coralline Crag at Sutton, a locality that has yielded so 
many of the smaller and more fragile species of Mollusca, numerous small or young 
individuals of this species may be obtained. My largest specimen was found in the 
Red Crag at Walton Naze, and measures an inch in its transverse or largest diameter 
but it is an old and somewhat mutilated individual. 
When my Catalogue was compiled this was considered to be a distinct species, in 
consequence of a difference in the size of the ligamental area, as in the Crag shell it is 
smaller than in the generality of recent specimens, the resemblance was, however, so 
great in all other respects, that the name of /actanea was given from its near 
relationship. I have since seen specimens of the recent shell in which this distinction 
is lost, and have therefore now united it with the long-known recent species. My 
specimens from the Crag are very regular in form, and I have not met with any 
fossils resembling the distorted varieties which have been erected into species by 
Payraudeau under the names of 4. Quoyii and A. Gaimardii, the greatest variation 
being slight differences in proportional dimensions, some occasionally being rather 
more transverse than others. F 
Arca nodulosa, Miller, given as an inhabitant of the Seas of Norway, by Dr. Lovén, 
corresponding probably with the Calabrian fossil 4. aspera, Phil., appears to differ 
from our shell in being larger and broader on the posterior half, with a more deeply 
