PHYLACTOLAEMATA. 567 



Tribe 1. HALCYONELLEA. Zoarium fleshy or membranous. Zooecia 

 developed by budding from other zooecia, and not from the internodes of a 

 stolon. 



Fam. 1. Alcyonidiidae. Zooecia more or less closely united, immersed in 

 an expanded and adherent gelatinous crust, or forming an erect cylindrical or 

 compressed zoarium ; oritice closed by the mere invagination of the tentacular 

 sheath ; not protected by external labia. Alcyoniclimn Lamx. 



Fam. 2. Flustrellidae. Zooecia immersed in a gelatinous crust ; orifice 

 bilabiate. Larvae with a bivalve shell. Flustrella Gray; F. hispida Fabr., 

 on Fuci between tide-marks. 



Fam. 3. Arachnidiidae. Zooecia usually more or less distant, membranous. 

 Arachnidium Hincks. 



Tribe 2. STOLONTFEHA. Zoarium horny or membranous. Zooecia de- 

 veloped by budding from the internodes of a distinct stolon or stem. 



A. All the tentacles erect. 



Fam. 4. Vesiculariidae. Zooecia contracted below, not closely united to the 

 stem at the base, deciduous, destitute of a membranous area. Zoarium repent 

 or erect. All with gizzard except Fan-ella. Vcsicularia, J. V. Thompson ; 

 Amathia Lamx. ; Zoobotryon Ehr. ; Bowerbankia Farre ; Avenella Dalyell ; 

 Farrella Ehrenb. 



Fam. f). Buskiidae. Zooecia contracted below, not continuous with the 

 creeping stolon, with an aperture on the ventral surface. Euskia Alder. 



Fam. 6. Cylindroeciidae. Zooecia not contracted below, closely united to 

 the stem at the base, not deciduous ; destitute of a membranous area. Cylin- 

 droecinm Hincks ; Anguinella v. Ben. 



Fam. 7. Triticellidae. Zooecia horny, with an aperture and membranous 

 area on the ventral aspect ; borne on a rigid peduncle, to which they are attached 

 by a movable joint, deciduous. Triticella Dalyell ; Hippuraria Busk. 



B. Two of the tentacles everted. 



Fam. 8. Valkeriidae. Zooecia contracted below, deciduous, destitute of 

 a membranous area. Valkeria Fleming. 



Fam. 9. Mimosellidae. Zooecia contracted below, movable, deciduous, with 

 an aperture on the ventral side. Mimosclla Hincks. 



Fam. 10. Victorellidae. Zooecia originating in an enlargement of the creep- 

 ing tubular stem, with which they are continuous at the base ; above free 

 and cylindrical ; not deciduous. Victorella S. Kent, fresh-water form, with 

 hibernacula. Paludicella Gerv. is allied here. 



Order 2. PHYLACTOLAEMATA. 



Fresh-water Polyzoa with horseshoe-shaped lophophore and epistome. 



The Phylactolaemata are mainly distinguished by the bilateral arrangement 

 of the numerous tentacles on the two-armed lophophore. There is always present 

 above the mouth a movable tongue-shaped process the epistome, whence the 

 name given by Allman to this sub-order. The zooids are usually of considerable 

 size, and are all alike (i.e. there is no polymorphism). The body-cavities of the 

 zooids of a colony are in wide communication, and the colonies are ramified or 

 massive, often transparent, and of a horny, or leathery, or gelatinous con- 

 sistency. Statoblasts are present. The cerebral ganglion contains a cavity 

 which is developed as a pit in the ectoderm of the bud. 



