39 
MAGAS. 
Gen. Char. An equilateral unequalvalved bivalve ; 
one valve with an angular sinus along an in« 
curved beak ; line of the hinge and back of the 
other valve straight,, with two projections near 
the middle. 
A partial longitudinal septum with appendages 
attached to the hinge within. 
This new Genus has the general contour of the plain 
Terebratulae figured in tab. 15; but attention to the parts 
about the hinge soon distinguishes it. The beak has no 
circular perforation as in them ; but there is a large qua- 
drangular foramen, two sides of which are formed by two 
projections from the straight back of the flatter valve, and 
the other two run along to the point where they meet; on 
each side of it is a flat space extending from the line of 
the hinge, which is much longer than the foramen, to the 
apex : if the valves be separated the foramen is divided 
into two angular sinus’s, that in the beaked valve being 
much the largest. In the middle of the shell rises a thin 
longitudinal septum reaching from one valve to the other ; 
the upper part of it arches over to the hinge, the front of 
it is perpendicular, on each side are two shelf-like ap- 
pendages, one over the other, the upper ones united by 
slender processes to the hinge. I know of but one species, 
some variation in these particulars may be expected in 
others, but the general structure is sufficiently remarkable 
to warrant the establishment of the Genus.* Most 
* It is not unlikely that Martin’s Anomites glaber and others resembling 
it, the internal structure of which I have not been able to examine, may 
belong to this Genus. It were much to be wished that some person would 
publish an account of the curious internal appendages of these shells. 
