99 
NAT1CA patula. 
TAB. CCCLXXIIL 
Three lower figures* 
Spec. Char. Hemisphceroidal, smooth, spire 
small, depressed ; umbilicus open containing 
a spiral ridge. 
The last whorl is very large and expanded, so as to give 
the entire shell the form of half a flatted spheroid cut 
along its axis. The surface is smooth, or so obscurely 
striated that it is difficult to persuade oneself that the 
striae are worn away, I speak of concentric striae ; the 
lines of growth are visible enough. The umbilicus is 
large, and not quite half filled by a large callus, that 
does not spread over it, and is accompanied by a smaller 
one, which forms a spiral ridge. The spire occupies less 
than a fifth of the shell, and is barely relieved from the 
general surface of the last whorl. 
Found in the Suffolk Crag at Ipswich, by Mrs. Cob- 
bold, generally about an inch wide, but sometimes, as 
specimens lent me by the Rev. G. R. Leathes prove, 
an inch and a half; the lower figures exhibit these 
specimens. 
NATICA striata. 
TAB. CCCLXXIIL 
Two upper figures . 
Spec. Char. Subhemisphcerical, smooth; spire 
small, depressed umbilicus open; base con- 
centrically striated. 
Greatly resembling the last, but not so much expan- 
ded ; the spire is rather more prominent, the concentric 
strim are impressed, but as they are liable to be lost by 
