Grenvus.—GASTROCH-ENA. Lam. 
Equivalve, somewhat wedge shaped, with avery large, 
oval, oblique, anterior opening between the valves ; 
the posterior extremity nearly closed ; hinge linear, 
marginal and toothless. 
G. Moprorina. Lam. 3.—Mya Dusia. Pen. 4. 
t. 44. p. 82.—Mont. p. 28.—G. Puoxapia. Turt. 
B.t.2.f.8, 9. p. 18.—G. Hans. Fl. p. 458.— 
Oblong, opaque, dirty white, finely striated concentri- 
cally, margin from the beak to the ligament nearly 
straight, then rounded anteriorly ; the oblique postezior 
truncation extended beyond the middle of the ventral 
margin; a narrow border in front of the beaks (which 
are nearly terminal and rather prominent) where ‘the 
valves are in contact. 4...1. In Limestone, near 
low water mark. 
Grenus.—GALEOMMA. Turton. 
Equwvalve, equilateral, transverse, with a large open 
gape at the ventral margin; hinge without teeth ; 
ligament partly internal. 
G. Turton. Turton. in Z, J. 2. p. 362. t. 13. f. 
1.—Desh. in Lam. 6. p. 180.—Sow. f. 1, 2, 3.~- 
Tumid in the middle and gradually sloping to the 
sides which are rounded and closed, dull milky white, 
the surface covered with short close-set transverse 
B 3 
