342 



MOLLUSCOIDEA— BRYOZOA 



PHYLUM V 



sisting 



of anastomosing brandies, which form a regular, round -meshed network. 

 Zocccia in two or more rows. Devonian to Permian. 



Ptiloporella, PHloporina Hall. Silurian and Devonian. Reteporina d'Orb. 

 Devonian and Lower Carboniferous. Anastoviopora Simpson. Devonian. 



Family 3. Acanthocladiidae Zittel. 



Zoaria poriferous on one side only, pinnate or formimj fenestrated expansions ; con- 

 sisting of strong, central stems ivhich give off numerous, smaller, lateral branches from 

 their opposite margins. The lateral branches are free or unite with those of the next 

 stem. Non-poriferotis dissepiments absent. Zocecial characters mosthj as in the Fene- 

 stellidae. Silurian to Permian. 



Pinnatopora "Vine. 



^^f!M 





^ 



{Glauconome auct., non Goldfuss) (Fig. 500, b, c). Zoaria 

 small, delicate, with short, free, lateral 

 branches given off frequently at regular 

 intervals. Cells in two rows, one on 

 each side of a moderate median keel. 

 Silurian to Permian. 



Septopora Prout. Zoaria fenestrated, 



flabellate or leaf-like. Primary branches 



numerous, increasing by bifurcation or 



interpolation ; the lateral branches 



\ '^^ff ^Bd!^*'^^ ^ %/^ uniting with those of adjacent stems. 



V "^Ir y^ ^^^^ l.m-i^ Reverse iisually with fine striae and 



scattered dimorphic pores. Celluliferous 

 side with two rows of zooecia arranged 

 as in Pinnatopora. Chester Group and 

 Coal Measures. 



Acanthocladia King (Fig. 500, a). 

 Like Pinnatopora, liut larger, stronger, and with three or more ranges of cells. Coal 

 Measures and Permian. 



Synocladia King. Differs from Septopora in the same manner as the preceding 

 differs from Pinnatopora. Permian. 



Ptilopora M'Coy {Dendricopora Koninck). Zoaria pinnate, the central branch 

 much stronger than the oblique lateral branches, which are united hj dissepiments. 

 ZocEcia in two ranges. Devonian and Lower Carboniferous. 



Diploporaria N. and B. {Diplopora Young). Essentially a Pinnatopora without 

 lateral branchlets. Carboniferous. 



Fig. 500. 



a, Acanthocladia fruticosa Ulr. i/j. 

 tenuiramosa Ulr. '/i. c, P. vinei Ulr. 

 Ulrich). 



\b, Pinnatopora 

 i/i and 9/i (after 



Family 4. Arthrostylidae Ulrich. 



Zoaria articukUed, co7isisting of numerous sub-cylindrical segments united into small 

 pinnate or bushy colonies, or of continuous, dichotomonsly divided branches. Zoo-cia sub- 

 tubular, more or less oblique, radially arranged about a central axis, and opening on all 

 sides of the segments ; or one side may be non-celluliferous and longitudinally striated. 

 Ordovician and Silurian. 



Arthrostylus Ulr. (Fig. 501, d, e). Zooecia bushy, dighotomously branching, the 

 whole consisting of numerous exceedingly slender, equal, subquadrate segments, 

 united by terminal articulation. Zooecia usually arranged in three rows between 

 longitudinal ridges ; the fourth face with longitudinal striae only. Ordovician. 



^Helopora Hall (Figs. 501,/; 502). Like the preceding, but the segments are 

 larger, and have zooccial apertures on all sides. Ordovician and Silurian. 



