336 



MOLLUSGOIDEA— BRYOZOA 



PHYLUM V 



iiiucli less distinct than in }itcno]3ora. Acautliopores and mesopores absent ; perforated 

 diaphragms numerous. Lower Carboniferous. 



Liodema Ulr. (Fig. 488). Ordovician to Coal Measures. Lioclemella Foerste. 

 Ordovician and Silurian. Orhifora Eichwald (Fig. 489, a, h). Ordovician. 



Fl(i. 488. 



Liodema foliata 'U\t. Keokuk Group; Illinois. ^-1, Vertical section, 21 /j. /;, Tangential section, '-^l^. 

 C, Portion of wall and acanthopore, 38/^. D^ Interstitial cell,i-'Vi (after Ulricli). 



Fig. 489. 



a, Orbipora distineta Eichw. Section, i4/j. h^ 0. acanlhoponi Bass, i-i/i. c, d, Esthoniopora communis Bass. 



Ordovician ; Baltic Provinces, s/j (aftei- Bassler). 



Esthonioimra Bassler (Fig. 489, c, d). Zoarium massive ; zocccia with semi- 

 diaphragms ; no mesopores or acantliopores. Ordovician ; Esthonia. 



Suborder B. INTEaHATA Ulricli and Bassler. 



Trepostomata in which the boundaries of adjoining zooecia are sharply defined by a 

 ivell-marked, dark-coloured divisional line. 



Family 5. Amplexoporidae Ulrich. 



Zoaria ramose, discoidal, massive or bifoliate. Zooicial tubes comparatively simple, 

 prismatic, with a well-marked divisional line between adjoining tubes. Mesopores 

 practicidly absent, but small abortive cells sometimes found among the large zooxia 

 forming the inonticules. Acanthoiwres generally abundant, sometimes quanting. Ordovician 

 to Devonian. 



Amplexopora Ulr. Zoaria ramose. Acanthopores always present, varying m size 

 and number. Diaphragms complete, horizontal. Ordovician and Silurian. 



Monotrypclla Ulr. Like the above, but without acanthopores. Ordovician to 

 Devonian. 



