200 AMERICAN MARINE GONCHOLOGY. 
the beak and extending about one-third the length of the shell; 
heemal valve with a mesial septum of about the same length 
extending forward from the beak. 
1. G. PYRAMIDATA, Stimpson. Fig. 551. 
(Lingula ) Am. Journ. Sci., xxix. 444. 1860. 
Shell greenish-white, ovate, elongated, convex ; base subtruncate ; 
surface smooth and glossy ; incremental lines inconspicuous. 
Length 22, width 9 mill. 
North Carolina. 
The mantle has well-developed marginal setz, those on either 
side, at the extremity longer than the rest, equalling in length 
one-third the width of the shell. There are two black spots on 
the margin of the mantle at the extremity. Peduncle, thick, 
muscular, hyaline with an opaque axis, three times the length of 
the shell. 
This species has been found, so far, unattached. It is extremely 
active in its motions when disturbed, and has the power, as 
described by Mr. Morse, of burrowing in and travelling over the 
sand by contortions of the peduncle and movements of the sete. 
Furthermore, the soft parts secrete a mucus to which grains of 
sand adhere, forming a “sandtube” of an extremely ephemeral 
nature, which sometimes extends over part of the valves. 
