274 



MOLLUSCOIDEA BRYOZOA 



SUB-KINGDOM V 



Petigopora, Ulrich. Small parasitic species having strong acanthopores but no 

 mesopores, and only a few diaphragms. 





FIG. 454. 



jSOL 



Dekayella dbscura, Ulr. Cincinnati, Ohio. Tangential 

 and vertical sections, * 4 /i (after Ulrich). 



FIG. 455. 



Dekayia aspero, Edw. 

 and H. Cincinnati, O. 

 Tangential section, n/j. 



Family 3. Calloporidae. Ulrich. 



Zoaria ramose, sub-frondescent, massive, or discoidal. Zoce.cial apertures generally sub- 

 circular and separated more or less completely by angular mesopores; at other times poly- 



FlG. 456. 



A, B, Callopora elegantula, Hall. Niagara ; Indiana. Vertical and tangential sections, u/i. C, D, C. multi- 

 tabulata, Ulr. Trenton ; Minnesota. C, Vertical section, T/I. D, Surface having zooecia open (7/j), and preserv- 

 ing zocecial covers ( 14 /i). 



gonal, when the mesopores are few or wanting. Zoo3cial tubes thin-walled, attaining their 

 full size slowly. Acanthopores wanting. Ordovician to Devonian. 



In this family the proximal ends of the tubes arising in the axial or "immature" region 

 have the character of mesopores. The diaphragms are rather closely arranged in the tapering 



FIG. 457. 



FIG. 458. 



Monotrypa magma, Ulr. Lower Trenton ; 

 Illinois. Transverse and vertical sections, 7/i 



Diplotrypa IfV.v/o/u, Ulr. Cincinnati Group ; Manitoba. 

 Tangential and vertical sections, U/i (after Ulrich). (after Ulrich). 



proximal end, then few or wanting for a considerable distance, and finally become crowded in 

 the peripheral or mature region. 



