276 MOLLUSCOIDEA—BRYOZOA SUB-KINGDOM V 
Family 5. Constellariidae. Ulrich. 
Zoaria ramose, frondescent, laminar, or encrusting. Zoecial tubes thin-walled and 
prismatic in the axial region, thicker and sub-cylindrical in the peripheral; mpertures 
rounded, the peristomes slightly elevated. Mesopores angular, abundant, generally isolating 
the zowcia, at intervals gathered into usually stellate clusters; closed at the surface, the 
closure with numerous perforations. True acanthopores wanting, but small hollow spines 
or granules often very abundant. Diaphragms straight and complete in both sets of tubes. 
Ordovician and Silurian. 
Constellaria, Dana (Fig. 461). Zoaria growing erect from a basal expansion which 
is attached to foreign bodies. Surface with depressed stellate maculae, the spaces 
between the rays elevated and occupied by two or three short rows or clusters of 
A B C D 

Fia. 461. 
Constellaria florida, Ulr. Cincinnati, O. A, Vertical section. B, Tangential, showing aged condition. 
C, Average tangential section, all 14/;._ D, Branch of the natural size (after Ulrich). 
closely approximated zocecial apertures. Mesopores aggregated in the maculae, inter- 
nally with gradually crowding diaphragms. Ordovician. 
Stellipora, Hall (mon Hagw. nec Haime). Differs from the above in its encrusting 
habit, and in having only mesopores in interspaces between the raised zocecial clusters. 
Ordovician, , 
Nicholsonella, Ulrich (Fig. 462). Laminar expansions, sometimes giving off 
flattened, intertwining branches or fronds. Interzocecial spaces wide, and with 

Fic. 462. 
Nicholsonella pulchra, Ulr. Lower Trenton; Tennessee. A, Surface, 7/;. 2, Vertical section, 4/);. C, Tan- 
gential sections at different levels, 14/; (after Ulrich). 
numerous mesopores, which have thicker and more numerous diaphragms than the 
zocecial tubes ; the spaces become filled up with age by’a calcareous deposit, rendering 
walls of mesopores unrecognisable, Ordovician. 
Idiotrypa, Ulrich ; (?) Dittopora, Dybowski. Silurian. 
