106 
PLEUROTOMA semicolon. 
TAB. CXLVI.—Fig. 6. _ 
Srec. Cuar. Turreted, elongated, striated, with 
many curved coste ; whorls swelled with a gra- 
nulated margin; base conical, decussated ; 
aperture ovate, beaked. 
Tur granule upon the margin of the whorls correspond 
With the coste, which are long, narrow, curved, and 
Swelled at the top: the beak is rather thick and obtuse ; 
aperture one-third the length. 
This does not appear to be a young shell although it is 
small, and as the characters are distinct and ripe, I was 
not willing to overlook it, not knowing of any other spe- 
cimen of the same species. Mr. Holloway found it at 
Stubbington. 
~ PLEUROTOMA colon. 
TAB. CXLVI.—Fig. 7 and 8. 
Spec. Cuar. Fusiform, striated; whorls concave 
above; with a crenulated margin, below with 
many rugged transverse ridges and small short 
longitudinal undulations; base conical ; aper- 
ture elongated. 
Tue transverse ridges alternate with the strie, and in 
some specimens divide the undulations into two small 
tubercles; the crenulations on the margins are also 
sometimes doubled in the same manner: the beak is 
obtuse; aperture nearly half the length of the shell ; the 
width is about one-third the length. 
Probably this is not rare at Barton Cliff, I have 
figured two varieties which I at first thought might be 
distinct species, but intermediate specimens have led me 
to alter my opinion : the chief difference is in the longitu- 
dinal undulations, which in fig. 7 are very small and 
formed into a double row of minute tubercles or punc- 
‘tums, while in fig. 8 they are larger and scarcely af- 
fected by the transverse ridges, but in it the margin still 
retains the double row of punctums or crenulations. Can 
these be young individuals of Murex turbidus of Brander ? 
Ihave named the three last species from the resem- 
blance of parts of their sculpture to the marks used ir 
punctuation, as they afford terms easily remembered. 
