THE MOUNT DESERT EEGION 309 



times this is covered over by a secondary calcification and 

 may appear rugose. No ovicells nor avicularia. 



Pyripora d'Orbig-ny, 1852 



Pyripoea catenulakia (Jameson), 1814. PI. 14, figs. 3-4. 

 (Wliiteaves, 1901, p. 96, for synonymy and references.) Taken 

 at stations 1, 4, 29, 39, 43, 48, 55, 58, 64, and 69 ; not uncommon 

 on pebbles. It is a North Atlantic species, occurring as far 

 north as Spitzbergen and Greenland and southward to the 

 Mediterranean. On the American coast it has not been re- 

 corded south of Cape Cod. 



Spreading in loosely arranged colonies over pebbles and 

 shells. Zooecia usually arranged in a single series, but fre- 

 quently these series coalesce into branches with 2 or 3 or 

 more series of zooecia. In general, the species resembles the 

 preceding, but the base of the zooecium below the aperture 

 is much more prolonged and often distinctly narrowed and 

 is imperforate and distinctly rugose and is without spines. 

 Lateral branches are frequently given olf at right angles. 



Alderinidae Canu and Bassler, 1927 

 Callopora Gray, 1848 



Callopora aurita (Hincks), 1877. PL 6, figs. 2-3. (Osburn, 

 1912, p. 230 {Membranipora.) Not at all common. Appar- 

 ently this species is more limited in its temperature range 

 than most other northern Bryozoa, though I have seen a speci- 

 men from Hudson Strait. It has not been recorded from 

 Greenland nor from the more northern coasts of Europe, 

 nor does it seem to enter the warmer waters of subtropical 

 regions. On the North American coast it is best developed 

 about Cape Cod. 



When ooecia are present the species is usually easy to dis- 

 tinguish by the paired avicularia placed at the sides of the 

 aperture pointed forward. The ovicell bears a triangular 

 area on its front when fully calcified. Infertile zooecia are 

 often quite irregular and possess a single avicularium near 

 the base of the zooecium pointed backwards. A pair of small 



