BRYOZOA OF WOODS HOLE REGION. 2 19 



A few specimens of this species dredged at Crab Ledge on pebbles. It has not hitherto been 

 recorded south of Canadian waters. 



Family LICHEXOPORID^ Hincks, 1880. 



Genus LICHENOPORA Defrance, 1823. 

 Lichenopora verrucaria (Fabricius). [PI. xvm, fig. 13, 133, i3b.] 



Fabricius 1780, p. 430 (Aladrefiora irrrucaria). 



Verrill and Smith 1874, p. 707 (Diastopora patina). 



Verrill 18753, p. 414, and 18790, p. 28 (Discopurclla verrucaria). 



Cornish 1907, p. 79. 



Zoarium usually a more or less circular disc, sometimes raised into a dome or otherwise modified; 

 usually entirely adherent, but sometimes stipitate, or with the edges projecting; size small, usually 

 about yi inch in diameter. Zooecia comparatively large, raised, in more or less regular radiating 

 lines but not connate ; usually with a well-developed rib on the side next to the center of the zoarium 

 and carried upward above the orifice into a pointed process; orifice large and oblique; marginal 

 zooecia not elevated. Ooecium an inflation of the surface; ooeciostome raised, with a rounded or 

 sometimes elliptical trumpet-shaped ooeciostome. The central area, which is free from zooecia, as 

 well as the spaces between the zooecia, is coarsely punctate. 



This little species is common at Crab Ledge on the stems of Bugula, Gemellaria and hydroids, as 

 well as on shells and stones. Taken also off Sankaty Head, Nantucket, Muskeget Channel, Nobska 

 Point in shallow water, Robinsons Hole, and near Gay Head. Recorded for Vineyard Sound off Vine- 

 yard Haven by Verrill. The species is a northern and arctic one and probably does not occur much 

 farther south on our coast. 



Suborder CHILOSTOMATA Busk, 1852. 



KEY TO FAMILIES. 



I. Nonincrusting forms, erect or creeping, usually more or less phytoid and flexible. 



1. A creeping stolon, with expansions from which arise the tubular zooecia (the polypide is more 



or less contained within the expansion); zooecium with a lateral membranous area and a ter- 

 minal orifice ^Eteidae. 



Zoarium phytoid or spreading, never stolonate 2. 



2. Zooecia uniserial or in two rows back to back, no appendages (avicularia or vibracula). . Eucrateidae. 

 Zooecia in two or more series, all facing the same way, appendages usually present 3. 



3. Zooecia closely united, appendages sessile Cellulariidae. 



Zooecia more loosely united, appendages pedunculate and jointed Bicellariidae. 



II. Incrusting forms, usually forming a well calcified crust on shells, stones, algae, etc., occasionally 



erect and foliose or branching, but when so rigid and solidly attached and usually arising from 

 an incrusting base. 



1. Front wall of zooecium depressed, membranous or partly bridged over by a calcareous shelf, zooecial 



borders raised Membraniporidae. 



Front wall of zooecium entirely calcified (except for a small pore in some cases) up to the oper- 

 culum 



2. Zoarium entirely encrusting; zooecial wall more or less traversed with transverse or radiating 



furrows Cribrilinidae. 



Zoarium encrusting or more or less erect; front wall of the zooecium often porous, but never regu- 

 larly grooved transversely or radiately 3- 



3. A small pore situated in the midline of the front wall below the orifice .4. 



No median open pore, though not infrequently a small rounded avicularium may be so placed ... 5. 



