256 University of California Puhlications in Zoology. [Vol. 4 



KEY TO THE FAMILIES OF USTCKUSTING CHILOSTOMATA. 



1. Colony circular or oval, convex, probably having power of self 

 movement in the adult stage Selenariidae 



1. Colony adherent, immovable 2 



2. Margins of zooecia raised 3 



2. Margins of zooecia not raised 5 



3. Front wall depressed, wholly or partly membranous 



Membraniporidae 



3. Front wall depressed, calcareous, on each side below the orifice a 



thin place in the calcareous wall 4 



4. Ooecia bilobate Steganoporellidae 



4. Ooecia plain, not bilobate Microporidse 



5. Front wall calcareous, traversed by radiating furrows 



Cribrilinidse 



5. Front wall calcareous, not traversed by radiating furrows 6 



6. Front wall usually possessing a special pore 7 



6. Front wall calcareous not possessing a special pore 8 



7. Orifice tubular, pore, when present, circular Porinidae 



7. Orifice semicircular, lower margin straight, special pore semi- 



circular ; Microporellidas 



8. Zooecia acquiring a secondary orifice by growth of peristome 10 



8. Zooecia with simple orifice 9 



9. Orifice with sinus on lower margin Myriozoidae 



10. Zoa:>cia urceolate, erect, or subereet, heaped together.... Celleporidae 



10. Zooecia not urceolate, and not heaped together irregularly 11 



11. Zooecia (a) with large orifice contracted near the lower margin, 



or, (b) with secondary orifice channelled in front, or, (c) with 

 primary orifice possessing a well developed niucro or tooth 



.Escharidae 



Membraniporidae Smitt. 



CelleporidcE (part) Johnston, 1847. 

 Memhramporidre. (part). Busk, 1854. 

 Flmtrellaridw (part) d'Orbigny, 1850-52. 

 Flustrellidce (part) d'Orbigny, ibid'. 

 Flustrinidce (part) d'Orbigny, ibid. 

 ElectrinidcB (part), d'Orbigny, ibid. 

 Membraniporidce Smitt, 1867. 

 Membraniporidce, Hincks, 1880. 



Zoarium calcareous or membrano-calcareons, incriisting. 



Zooecia forming a continnous expansion, the front wall more or 



less membranous. 



