BIVALVIA. 45 
margin; the exterior is covered with numerous irregular striz or striated coste, 
rough or scabrous, radiating in an undulating direction, extending from the extreme 
edge of the posterior side to the anterior, where, for a small space, it is naked or 
destitute of strize, those on the posterior are fine and closer set, becoming larger and 
more distant as they approach the anterior, where they are rough and project beyond 
the margin. The hinge line is less oblique than in evi/is, and is narrower, which per- 
haps it would be, if not a different species, corresponding thus with the more narrow 
form of the shell, but the ligamental area is deeper from the umbo inwardly, while the 
gape on both sides is larger than in that shell, and the whole contour in this is so dif- 
ferent that, judging from the specimens which I possess, they cannot be united without 
an extension of variation greater than is generally permitted to species of this genus. 
In the recent state, in the more northern parts of the British seas, it attains a greater 
magnitude than is given by the dimensions of our fossil, which may not, possibly, be a 
full-grown individual, although its gape is wide, a character of the adult shell; it is said 
one inch and three quarters is not an uncommon size in the recent British specimens, 
whilst those found at Guernsey are less, resembling in this peculiar our Crag fossil. 
3. Lima Loscomsu, G. Sowerby. Tab. VII, fig. 1, a—e. 
PEcTEN FRAGILIS. Mont. (not Chemnitz). Test. Brit. Sup., p. 62, 1808. 
OsTREA FRAGILIS. Turt. Conch. Dict., p. 131, 1816. 
Lina BuLtata. Turt. (not OstREA BuLLATA, Born.). Brit. Biv., p. 217, t. 17, figs. 4, 5. 
— —_ Thorpe. Brit. Mar. Conch., p. 114, 1844. 
— a Phil. En. Moll. Sic., vol. ii, p. 56, t. 16, fig. 2, 1844. 
— Loscompi. G. Sow. Genera of Shells, No. 17, Lima, fig. 4. 
_— _ Reeve. Conch. Syst., pl. 112, fig. 4. 
— _ G. Sow. Thesaur. Conch., vol. i, p. 86, pl. 22, figs. 20—22. 
—— _ Lovén. Ind. Moll. Scand., p. 32, 1846. 
— — Forb. and Hanl. Hist. of Brit. Moll., vol. ii, p. 265, pl. 53, figs. 1—3. 
— —_— Alder. Cat. Moll. North. and Durh., p. 78, 1848. 
— FraGiLis. Brown. Ilust. Conch. Gr. Brit., pl. 31, figs. 6-7, 1827. 
a — Forbes. Mag. Nat. Hist., vol. viii, p. 594, fig. 65. 
— — Id. Malac. Monen. p. 40, 1838. 
— — S. Wood. Mag. Nat. Hist., New Series, vol. iii, p. 235, pl. 3, fig. 3, 1839. 
Spec. Char. Testa tumida, oblique-ovata, inequilaterd, tenui, fragili; utroque latere 
perparvulum hiante, striatd, striis tenuissimis, alternatis, undulatis, cardine obliquo. 
Shell tumid, obliquely ovate, inequilateral, thin and fragile; very slightly gaping 
on either side, covered with fine striz, slightly undulating, and alternately larger and 
smaller; cardinal area oblique and small. 
Greatest Diameter, % of an inch. 
Locality. Cor. Crag, Sutton and Ramsholt. 
Red Crag, Walton Naze. 
Recent, Britain, Norway, and Mediterranean. 
