†Ptychocaulus Perner 1925

Perner 1925. [title not given] Systeme Silurien du Centre de la Boheme., Barrande J. Prague 4 tome 2 1907 pp. 1-380 pls. xc-clxxv 4 3 1911 pp. 1-390 pls. clxxvi-ccxlvii., 1925: pp. 1-380. Chapter pagination: pp. 1-380