. Bulletin - New York State Museum. Science. 258 NEW YORK STATE MUSEUM lateral margins rather directly convergent. The ventral valve is elevated at the beak, the cardinal area being rather high and curved, and the median part of the shell elevated. 3 Surface. The median sinus has a width of from two to two and five tenths lateral furrows, its sides being highly divergent, slop- ing abruptly to the bottom whch is sometimes quite sharp. The pri- mary plications are conspicuous and elevated. On the sides there are four, rarely five, plications, in extreme cases greatly subordi- nated to the media
. Bulletin - New York State Museum. Science. 258 NEW YORK STATE MUSEUM lateral margins rather directly convergent. The ventral valve is elevated at the beak, the cardinal area being rather high and curved, and the median part of the shell elevated. 3 Surface. The median sinus has a width of from two to two and five tenths lateral furrows, its sides being highly divergent, slop- ing abruptly to the bottom whch is sometimes quite sharp. The pri- mary plications are conspicuous and elevated. On the sides there are four, rarely five, plications, in extreme cases greatly subordi- nated to the median ones and separated by broad furrows. The sculpture of the surface consists of rather coarse and moderately distant concentric lines which may become lamellose. 4 Interior. The dental plates are as in S. cymindis. The muscle scar of the ventral valve is deeply impressed and sharply defined, specially in old shells where the test is thickened in the umbonal region. The removal of this thickened shell leaves in- ternal casts with a prominent muscle area, the surfaces adjoining which are pustulose. There is no median septum in this valve. In young shells the ribs are sharp on the internal cast but are rounder on old shells. The features here summarized constitute an expression not rep- resented in the Appalachian faunas and so far as we can ascertain not exactly reproduced in the Coblentzian. Lower Devonic. Presque Isle stream. Chapman Plantation, Me. S|)irifer aroostookensis nov. This shell is characterized by its broad, flat ribs with very nar- row, radial furrows, in which respect it is remarkably similar to. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original New York State Museum; New York State Museum. Albany : New York State Education Dept
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectscience, bookyear1887
