516 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 14 



Myriozoella plana (Dawson), 1859 

 Plate 64, figs. 1-2 



Lepralia plana Dawson, 1859:256. 

 Myriozoum crustaceum Smitt, 1867:18. 

 MyriozouTH planum, Hincks, 1892:157. 

 Leieschara plana, Norman, 1903 :1 10. 

 Myriozoum crustaceum, Robertson, 1908:295. 

 Myriozoum crustaceum, Osburn, 1919 :609 ; 1923 :9D. 

 Myriozoella Crustacea, Osburn, 1932 :16. 



Zoarium encrusting, often multilaminar, on various objects, the 

 colonies often an inch or more in breadth on shells and stones. The 

 zooecia are flat and indistinct, except in the youngest stages when they 

 are slightly inflated and the outlines of separation are visible. The 

 frontal is a coarse tremocyst with large infundibular pores which leave 

 a reticulated surface. The aperture is somewhat more than a semicircle, 

 varying slightly in length and breadth, the proximal aperture straight 

 with a narrow deep sinus. On either side of the aperture is a rounded 

 avicularium of moderate size, without hinge bar; immersed or slightly 

 elevated ; rarely wanting on one or both sides. 



The ovicell is hyperstomial, deeply immersed in the base of the 

 distal zooecium but usually evident as a distinct rounded swelling, 

 perforated like the frontal. 



Smitt, in describing Myriozoum crustaceum, probably overlooked 

 Dawson's description of Lepralia plana. Since that time the species has 

 been recorded under both names. Objections have been made to the 

 use of Dawson's name on the basis of inadequate description. However, 

 Hincks (1892:157) remarks: "Dawson's diagnosis may not be as full 

 and minute as we should now desire, but it indicates the general charac- 

 ter of the species, and his description has as good a claim to be retained 

 as those of a large proportion of the older writers." Norman ( 1903 :1 10) 

 also writes: "Dawson's description of Lepralia plana was very inade- 

 quate; but I have seen specimens named by him, and there can be no 

 doubt as to the species which he intended." Furthermore there is no 

 other species in the area dredged by Dawson which could possibly be 

 confused with it. 



The species is a common circumpolar form, extending its range down 

 the east coast of Canada to the Gulf of St. Lawrence, and on the west 

 coast to southern Alaska. Robertson recorded it from Yakutat, Orca, 



