44 
PALAEONTOLOGY OF NEW YORK. 
The exterior surface bears a median sinus and more or less distinct lateral 
plications. On the interior the dental lamellae are strongly developed and 
converge rapidly, meeting a median septum from the bottom of the valve. 
The union consists of a lateral junction of the dental lamellae with the septum, 
the latter continuing for a short distance beyond the point of confluence as a 
vertical ridge, always apparent in the bottom of the spondylium thus formed. 
At the point of union these three plates constitute a tubular chamber which 
has no external opening in older shells, and may be filled by organic deposit.* 
The dental plates are shorter than the septum, the latter, at its base, extending 
beyond the center of the valve, its anterior margin being concave and its inner 
extremity acute and produced. 
Brachial valve very shallow, with narrow, inconspicuous cardinal area Sur¬ 
face plicated as in the opposite valve. Cardinal process consisting of a double 
apophysis on the sides of which are strong, divergent crural plates The spiral 
cones are elongate-fusiform, each coil attaining its greatest diameter just below 
the center. They are directed obliquely upward and backward towards the 
middle of each lateral slope of the pedicle-valve. The loop is continuous, its 
branches being directed upward and forward, uniting at their extremities. The 
muscular impressions comprise two oval anterior, and fainter posterior scars. 
The surface ornamentation consists of radial plications which may cover both 
fold and sinus; in rare instances the lateral plications are absent. The con¬ 
centric growth-lines are sometimes tine and crowded, at others distant and 
lamellose; occasionally the surface is coarsely papillose. Shell substance 
strongly punctate. 
Type, Calceola heteroclita, Defrance. Middle Devonian. 
Observations. With the appearance of this genus in the faunas of the 
Niagara group, comes the earliest indication of shell punctation in the spiriferoid 
brachiopods. It has been observed that when punctation appears among the 
Spirifers themselves, as in Martinia, Martiniopsis, etc., it is late in the history 
* In the species C. rostrata, Hall, the median septum appears to traverse the tubular chamber, some¬ 
times in an', irregular way, dividing it into two lateral compartments. This structure may prove to be 
the homologue of the unsupported tube in SyRiNGOTHVRis. 
