177 
from Avignon, where they are said to be sometimes larger, 
even ten inches or more. Probably they are as large in 
England in places from whence I have received only - 
smaller specimens, as Cardiff Castle, and Pickeridge Hill, in 
South Wales, from which latter place I have received 
abundance and variety by favour of Miss E. Hill, who 
first noticed those interesting quarries, being conducted there 
by an observing mind, upon seeing the stony fragments 
brought to the road side from Boston House, and finding 
upon enquiry that it was built of stone brought from that 
place about 250 years since. Several new and curious 
productions are found these deserving the attention of . 
the Geologist, as to the strata, &c. Among them are a 
variety of Gryphites and flattened Ammonites, in what the - 
workmen called Blue and Grey Lyas; there are even 
- fragments of Pentacrini, Echinus spines, &c. and it may be 
worthy of remark that the striated Limestone, Brit. Min. 
tab. 345, is found there much as at Shotover. 
PLAGIOSTOMA spinosa. 
TAB. LXXVIII. 
Spec. Cuar. Obovate, longitudinally furrowed ; 
sides nearly equal, straightish; one valve spi- 
nous, spines half the length of the shell. 
ore EE 
Ove valve is more convex than the other, the flatter one 
being spinous; both are deeply and regularly furrowed 
both outside and within, the projections of the inside ter- 
minate in angular teeth near the edge. The spines; in 
(RLS,  VAty 
j iy 
V5 Fe 
