408 THE MEDALS OF CREATION. Cuap. XI. 
. M. striata, since the strie are peculiar), occurs in the Kim- 
meridge Clay, at Hartwell. 
Those species of Modiola, which excavate hollows in stones, 
and inhabit them, are arranged ina genus termed Litho- 
domus. The occurrence of these shells in the remaining 
erect pillars of the Temple of Jupiter Serapis (Wond. p. 
106), at Puzzuoli, has afforded important and unequivocal 
evidence of the physical mutations which that part of Italy 
has undergone. Two species of Lithodomi have been found, 
by Mr. Lonsdale, in the Oolite. 
Puooutapomya. Ly. p. 272, fig. 290.—This genus of shells 
(established by Mr. James De C. Sowerby in the Jfin. Conch. 
1826), comprises about twenty British fossils, all of which, 
with but two exceptions, occur in the Lias and Oolite. 
They are equivalved shells, with the posterior end short, 
and rounded, and the anterior elongated and gaping. ‘The 
surface is generally marked with ribs, or alternate elevations 
and depressions, diverging obliquely from the beaks to the 
margin. In the clay at Osmington and Radipole, near 
Weymouth, a large species (P. equalis, Min. Conch. tab. 
546) is abundant. The Oolite of Brora, in Scotland, con- 
tains several species. The only species found in our Chalk, 
is the beautiful shell (P. decussatum), figured Foss. South D. 
tab. xxv. fig. 3, and first discovered by me, in 1820, in a 
bed of Chalk Marl, which at that time was exposed at low- 
water, at the base of the cliff at Brighton, near the present 
entrance to the Chain-pier. The same species has since 
been found at Clayton, Hamsey, Southbourn, and other 
localities of the Marl. 
Puotas. Lign. 166, fig. 5, 6.—The common boring 
bivalve called Pholas, must have attracted the attention of 
every stroller by the sea-shore, from the numerous perfora- 
tions in blocks of chalk, and other limestones, occasioned 
