TO GEOLOGY. 157 
GENUS MUREX.  Linneus. 
JM. alternata. Plate 5. Fig. 163. 
Description. Shell subfusiform, turrited, longitudinally 
ribbed, armed with erect spines; substance of the shell 
thin; spire elevated, pointed at the apex; suture irregular ; 
spines tubular, alternately placed on and between the 
ribs ; whorls seven, flat above ; mouth entire, ovate. 
Length .8, Breadth .3, of an inch. 
Observations. This curious little Murer strongly re- 
sembles the M. pungens (Brander), plate 3, fig. 82, (M. 
fistulosus of Sowerby), and that under the same name, fig. 
81, (VW. tubifer of Lamarck and Sowerby). It differs, how- 
ever, from both. Having them in my cabinet, on com-. 
parison, I find our shell to be more elongate than either, to 
differ essentially from the fistulosus in having a longer 
spire and much smaller ribs, and the tubifer in having but 
one row of spines instead of four. The Murices with the 
mouth entire, were separated by Montfort, under the 
name of Typhis, and Cuvier has adopted it as a subgenus. 
It is remarkable that among so many new species of the 
various genera, only one Murex should as yet have been 
found in this stratum. In England forty-seven species 
have been observed, nearly the whole being from the 
London Clay and Crag. Eighty-nine species are men- 
