SUB-ORDER B 



TREPOSTOMATA 



271 



Filicea, d'Orb. (Laterocea, d'Orb.), (Fig. 447). Zoaria erect, with sub-cylindrical 

 branches bearing apertures on all sides. 



Zooecial tubes dilating outwardly, with 



FlO. 447. 



Filieea relata, Hagw. sp. Upper Cretaceous ; Maestricht, Holland. A, Branch, 1/1- B, Surface of same 

 enlarged. (', Vertical section (atter d'Orbigny). 



Family 12. Melicerititidae. 



Zoaria ramose, bifoliate, or uni-lamellate. 

 perforated walls. Front of zocecia 

 partly covered by a perforated plate. 

 Vicarious avicularia scattered among 

 the zocecia. Cretaceous. 



The members of this family differ 

 widely from the true Cyclostomata. 

 They may be Mesozoic representatives 

 of the Palaeozoic Cryptostomata, some 

 of which, particularly Proutella, they 

 greatly resemble. But, on the other 

 hand, the presence of avicularia, which 

 are as yet entirely unknown among 

 Palaeozoic Bryozoans, perhaps in- 

 dicates even stronger affinities with 

 the Chilostomata. 



Fia. 448. 



Structure of walls and 

 Ulr. 



parenchymal cord in Homotrypacallosa, 

 (A, 38/j); Stictoporella frondifera, Ulr. (B " 

 pora columnifera, Busk. Recent. (C, w/i.) 



and Rete- 



Semielea, d'Orb. (Reptelea, etc., d'Orb.) ; Eetelea, Clausimultelea, d'Orb. 



Elea, d'Orb. Flattened, branching, or anastomosing stems, or broad leaves, pori- 

 ferous on both sides. 



Meliceritites, Roemer (Escharites, Roeni. ; Inversaria, Hagw. ; Nodelea, Multeleu, 

 d'Orb.) Cylindrical branching stems, poriferous on all sides. 



Sub-Order B. TREPOSTOMATA. Ulrich. 1 



Zo(ecia directly superimposed upon one another so as to form long tubes intersected by 

 straight or curved partitions (diaphragms and cystiphragms), representing the covers and 



1 [Two regions of the zorecial tubes are distinguishable, an axial or " immature " region, in which 

 the diaphragms are remote, the walls thin, and the tubes prismatic through contact ; and a peri- 

 pheral or "mature " region, in which the tubes bend outward, the walls are thickened and otherwise 

 modified, the transverse partitions more abundant, and interzorecial elements (acanthopores, rneso- 

 pores, or mere strengthening tissue) are developed. 



Waagen and Wentzel and others erroneously assert that the mesopores and acanthopores, occur- 

 ring so commonly in this sub-order, are young zocecia or " corallites." With very few exceptions, 

 these really very different elements are not developed until the zoarium has reached the mature 

 stage, in which new zocecia cease to be given off. The origin of mesopores (i.e. all cells occupying 

 iiiterzocecial spaces, whether invested with separate walls or not) is due to the same necessity which 



