PLATE 42, 43, 44. 
4. The upper part of one of the columns broken from 
the foregoing. 
5. Another specimen in limestone. The figure shows 
only the side and base of the specimen. 
F. 44 FIG. 7 . 
CONCHYLIOLITHUS Arcites (cancellatus) sub- 
romboidalis decussatim aequaliter striatus, antice ob- 
liquus angulatus natibus remotiusculis. S. p. 
A fossil shell. Original an Area. The hinge straight, 
extending the whole breadth of the shell. Valves equal, 
somewhat rhomboidal; their anterior extremity sloped and 
angular ; the other end wore rounded ; the surface cancel- 
lated with longitudinal, and transverse, equal striae. The 
beaks small, placed nearer the rounded extremity. 
Not a common fossil. I have seen but few specimens of 
it, and those in limestone. That which is figured exhibits 
only one of the valves ; the inside filled with stone. 
