232 ROBERTSON [3 2 4J 



MEMBRANIPORA LINEATA Linnaeus. 



Membranipora lineata HINCKS ('80), pi. xix, figs. 3-6. 



Membranipora lineata SMITT ('67), pi. xx, fig. 23 ; Flor. Bry. pt. n, pi. 11, 

 fig. 62. 



Habitat. A small patch on Cellaria borealis. 



Local distribution. Orca, Prince William Sound. 



Geographical distribution. Common on the coasts of Britain; 

 Roscoff; Scandinavia, in shallow water, common; Baltic; Spitz- 

 bergen; Davis Strait, 100 fms. ; Iceland, 15-20 fms. ; Nova Zembla; 

 Kara Sea ; South Labrador ; Adriatic ; Florida ; New Zealand. 



MEMBRANIPORA UNICORNIS Fleming. 



Membranipora unicornis HINCKS ('80), pi. xx, fig. 4. 



Membranipora lineata 5, forma unicornis, BB, stadium longius adultum SMITT 

 ('67), pi. xx, fig. 30. 



Habitat. Upon other Bryozoa and on hydroid stems. 



Local distribution. Juneau; Yakutat; Orca; Houston-Stewart 

 Channel, Queen Charlotte Islands. 



Foreign distribution. Britain; Bohuslan; Spitzbergen; Green- 

 land; Nova Zembla. 



MEMBRANIPORA SPINIFERA Johnston. 

 Membranipora spinifera HINCKS ('80), pi. xix, figs, i, a, b, c. 

 Habitat. Upon a stone. 



Local distribution. Orca, Prince William Sound. 

 Foreign distribution. Abundant upon the British coast, France. 



MEMBRANIPORA SANDALIA sp. nov. 

 (PI. XX, figs. 9, 9, 9$; PI. XXI, fig. 10.) 



Habitat. Upon sponge. 



Local distribution. Yakutat. 



Zoarium forming a rather loose crust, brittle and delicate, and only 

 partially attached ; spreading out in a fan-shaped expansion, the ge- 

 latinous margin of which is often convoluted ; the apposed surfaces 

 often growing together and forming irregular ridges over the 

 colony. Zoecia oblong, quadrangular in the younger stages, much 

 narrowed below in the older, and disposed in alternate series. In the 

 adult stage, the upper half of the zoecial front is occupied by a mem- 

 branous area, containing the crescent-shaped orifice at its distal end. 

 The lower half is traversed by a network of calcareous lines or ribs 



