288 MOLLUSCOIDEA BRYOZOA SUB-KINGDOM v 



Family 10. Microporellidae. Hincks. 







Zoaria encrusting or erect, foliated or dendroid. Zocecial orifice more or less semi- 

 circular, with the lower margin entire; a crescentic or 

 circular pore on the front wall usually just beneath the 

 orifice. Cretaceous to Recent. 



Microporella, Hincks (Fig. 482). Zoarium encrusting 

 or erect, bilaminar. Margin of zooecia not elevated. 

 Orifice with a straight, entire lower border, frequently 

 with oval spines. Usually one semi-lunate or circular 

 pore beneath the orifice, occasionally two or three. 

 Tertiary and Recent. 



Diporula, Chorizopora, Hincks. Tertiary and Recent. 



? Monoporella, Hincks. Like Microporella, but with- 

 out special pores. Cretaceous to Recent. 



Microporella riuJis, Reuss sp. _ ., 



oiigocene; Soiiingen. Upper sur- family 11. Porimdae. d Orbigny, emend. Hincks. 



face, enlarged. 



Zoaria encrusting, or erect and ramified. Zooecia with 



a raised tubular or sub-tubular orifice, and frequently with a special pore on the front wall. 

 Cretaceous to Recent. 



Porina, d'Orb. Zoaria consisting of flattened or sub-cylindrical branches, celluli- 

 ferous on both sides, or encrusting. With age the spaces between the raised apertures 

 become filled with a porous calcareous deposit. Avicularia and ooecia occasionally 

 distinguishable. Cretaceous to Recent. 



Celleporella, Gray ; Anarthropora, Smitt ; Lagenipora, Hincks. Recent. 



Family 12. Escharidae. Hincks. 



Zoaria erect, unilaminate or bilaminate, foliaceous or ramose, or crustaceous, loosely 

 attached or adnate. Zoozcia urceolate, the front entirely calcified, without raised margins. 

 Orifice anterior, sub-circular to horseshoe-shaped, the lower border straight, broadly sinuate, or 

 notched. An elevated secondary orifice, with the lower margin dentate, channeled, or 

 enclosing an avicularium, often present, but no special pores. Cretaceous to Recent. 



This family embraces a large number of fossil and existing Bryozoans, and in its present 

 state can hardly be said to form a natural group. It is here that the much greater importance 

 of zocecial characters as compared with zoarial are particularly apparent ; inasmuch as one genus, 



or n many cases a species, as now generally understood, may include a considerable range of 

 zoarial types. To the palaeontologist the group offers exceptional difficulties, since generic 

 characters frequently depend upon easily abraded or obscure modifications of the orifice. 



Lepralia, Johnston (Fig. 483). Zoaria encrusting or rising into simple or branching 

 expansions, composed of one or two layers of cells. Zooecia usually ovate, the orifice 

 with a thin peristome and entire lower margin. Rare in Cretaceous, more abundant 

 in Tertiary and Recent. 



Porella, Gray. Zoaria encrusting or erect. Zooecia with a semi-circular primary 

 orifice ; the secondary (adult) orifice elongate, inversely sub-triangular, or horseshoe- 

 .shaped, and enclosing an avicularium with a rounded or sub-triangular mandible. 

 Tertiary and Recent. 



Smittia, Hincks. Zoaria encrusting, or erect and foliaceous. Primary orifice of 

 zooecia sub-orbicular, the lower margin with an internal median denticle. Secondary 

 orifice canaliculate below ; generally a small avicularium either within or just beneath 

 the sinus. Miocene and Recent. 



Mucronella, Hincks (Fig. 484). Similar to Smittia, but with simpler orifice, and 



