236 NEW YORK STATE MUSEUM 



the shell as to form radial rows of deep meshes which often alter- 

 nate in their position in adjoining rows. The meshes in C. i n c a r - 

 ceratum are much the larger transversely. The anterior ridge 

 is sharply elevated and crested, the anterior slope very abrupt, 

 excavated and striated by the elevated concentric lamellae which 

 here take on a radial attitude. The posterior termination is 

 extended and acute and the valves gape at this end. These speci- 

 mens show very clearly the structure of the sculpture or prismatic 

 layer of the shell in these species, which is rendered distinctly 



vs,-~ 



Conocardium incarceratum X3 



cavernous by the projection of the concentric growth in the form 

 of pronounced lamellae rising from the deep intervals between the 

 ribs and dividing these areas into series of elongate pit-shaped 

 meshes. 



I have been disposed to regard these shells identical with 

 C. rhenanum as described and figured by Beushausen [op. cii. 

 p. 402, pi. 30, fig. 5-8]. There is agreement between the two in 

 respect to size, form and radial markings but the lamellar surface 

 structure is not defined in sufficient detail to determine whether it 

 corresponds to that of the Dalhousie shell or that of C. incep- 

 t u m Hall. As there is a palpable difference herein we have pre- 

 ferred to give these shells a distinctive designation. Conocar- 

 dium rhenanum is from the Coblentz quartzite and the Upper 

 Coblentzian of the Rhine. 



Lower Devonic. Dalhousie, N. B. 



Lunulicardium ? convexum no v. 



Cardiform, beak anterior, outline obliquely orbicular. Surface 

 convex, elevated about the umbo, which is full and overarched, 

 abruptly deflected on the anterior slope. Anterior marginal curve 

 at first concave, thence rounding rather abruptly at the extremity, 

 posterior curve much broader and postlateral surface somewhat 



