Genera of the North American Palaeozoic Bryozoa. 547 



106 



Fig. 105. Arthroclema BilUngsi. natural size. 



Fig. 106. A. cornutum, one of the primary segments, showing lateral sockets. 



Fig 107. A. cornutum, four primary segments, natural size, and thi-ee x7, showing the 

 articulating sockets near the base of each. 



Fig. 108. Five of the secondary segments, natural size, and x7. 



Fig. 109. A. striatum, lateral view of a large and strongly striated primary segment, 

 xl8. 



Fig. 110. A secondary segment, xl8, a id tnd view of the preceding, xl8. 



Fig. 111. A. armatum, a complete segment of the secondary set, xl8. 



Fig. 112. A. cornutum, a primary segment, xl8. 



