40 
of the Terebratula have lines along the beak, in the 
same direction as the sinus in this, but the back of the 
flatter valve is arched, never straight ; this also wants the 
perforation in the beak. The resemblance of the arched 
septum to the bridge of a violin has suggested the generic 
name : to which valve this septum is attached I have not 
been able to ascertain, because I could not open the shell 
without breaking it. 
MAGAS pumilus. 
TAB. CXIX. 
Spec. Char. 
T- he beaked valve is hemispherical, smooth, with a cir- 
cular edge, and small incurved beak; the other valve 
nearly flat, with a long transverse straight back. 
Mr. Richard Taylor, jun. favoured me with specimens 
of this singular shell, found in the Chalk near Maudes- 
ley, Norwich. The construction being new to me I was 
glad to exhibit it, especially as it appears to be newly 
discovered in the chalk; the specimens, he observes, are 
sometimes smaller than No. 1, hut seldom larger than No. 2, 
3, and 4. The extraordinary interior construction I have 
only been able to give an imperfect idea of, not having an 
opportunity to examine sufficient specimens. When mag- 
nified the shell is found to be curiously punctured in a 
minute quincunx order, which appears to depend on the 
construction of it, as in most of the tribe related to the 
Terebratula; it is generally most apparent within the 
substance. 
