Family Calymenidae Burmeister

Subfamily Calymeninae Burmeister, 1843

"CALYMENE" Brongniart, 1822. " Calymene breviceps Raymond, Waldron Shale, Silurian, Niagaran, Waldron, Indiana (x2.6). (Gurley coll. of UCWM; loaned by FMNH.) Several complete individuals, rolled and unrolled.

Calymene niagarensis Hall (x2.8). Racine Formation in the Niagaran Limestone, Silurian, McCook, Illinois (RLS coll., id.; now at FMNH). Negative mold encrusted with dolomite crystals. In spite of the coarse grain of the surface, anatomical details of the exoskeleton are remarkably well preserved in this kind of fossilization. In this and other similar specimens collected by the author at the above locality, a hollow cavity is found in place of the stein kern.

Calymene celebra Raymond (x3.2). Joliet Formation in the Niagaran Limestone, Silurian, Lehigh, Illinois. (RLS coll., id.; now at FMNH.) Steinkern and its negative mold, specimen collected by Matteo Levi-Setti, at the age of four.

Side view of another example of Calymene celebra R ay m ond (x 4. 6), from Lehigh, Illinois. (RLS coll., id.; now at l-MNH.) The layer previously occupied by the exoskeleton is replaced by dolomite crystals. Specimen collected by Emile Levi-Setti, at the age of seven.

Negative mold of several Calymene celebra individuals (xl.l). Niagaran Limestone, Silurian, Wisconsin. (Loaned by FMNH.)

Calymene celebra Raymond (x3.6). Niagaran Limestone, Silurian, Grafton, Illinois. (UCWM coll.; loaned by FMNH.) An unusual association of complete individuals.

DIACALYMENE Kegel, 1927. Diacalymene clavicula

(Campbell) (x2.3). Henryhouse Formation, Hunton Group, Silurian (Cayugan). Lawrence uplift neat Ada, Oklahoma. (RLS coll.; now at FMNH.) The exoskeleton is replaced by calcite; the matrix is a soft siltstone. Several fractures due to compression in the sediment can be noticed.

Family Ulaenidae Hawle and Corda, 1847

Subfamily Bumastinae Raymond, 1916

BUMASTUS Murchison, 1839. Bumastus ioxus (Hall) (x5.6). Niagaran Limestone, Silurian, Grafton, Illinois. (Gurley coll. of UCWM; loaned by FMNH.) Internal mold, coated with dolomite crystals.

Bumastus ioxus (Hall) (xl. 3). Rochester Shale, Silurian, Lockport, New York. (J. Hall coll. of UCWM; loaned by FMNH.) Exoskeleton partly preserved.

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