640 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 14 



Diplosolen obelium, (Johnston), 1838 



Plate 73, fig. 1 



Tubulipora obelia Johnston, 1838:269. 

 Diastopora obelia, Hincks, 1880:462. 

 Berenicea obelia, Okada, 1917:352. 

 Diastopora obelia, O'Donoghue, 1923:14. 

 Diplosolen obelium, O'Donoghue, 1926:24. 



The zoarium is thin and flat, rounded or irregularly lobate. The 

 zooecia are embedded for most of their length, though the semierect 

 peristomes project well above the surface ; the aperture is round or 

 slightly elliptical, 0.08 to 0.10 mm in diameter. In Alaska specimens 

 the aperture is noticeably larger, 0.10 to 0.12 mm in diameter (var. 

 arctica Waters, 1904a :1 71) than in southern specimens, but there seem 

 to be no other differences of importance. The nannozoids are similar in 

 form to the autozoids, but are minute in size ; their peristomes are much 

 shorter and are only about 0.03 mm in diameter. 



The ovicell is considerably inflated, varying in size, oval or arcuate, 

 transverse, and encloses a number of peristomes of both autozoids and 

 nannozoids (as few as 2 and as many as 20 have been counted). The 

 ooeciostome is isolated, short, its aperture rounded and intermediate in 

 size between those of the autozoids and nannozoids, usually more or 

 less central in position. 



It is a well-known North Atlantic species, extending into the Arctic, 

 and reported from Japan. On the Pacific coast it has been recorded by 

 O'Donoghue from several places in British Columbia and from the San 

 Juan Islands in Puget Sound. 



Hancock Stations: 1194-40, 43 fms, and 1294-41, 34 fms, at Santa 

 Cruz Island, southern California. Also among the collections are speci- 

 mens from Puget Sound; from Alitak Bay, Alaska (U. S. Fisheries 

 Alaska Crab Investigation) ; from Nash Harbor, Nunivak Island, 

 Alaska; from the Bering Sea, and from Point Barrow, Alaska (Arctic 

 Research Laboratory, G. E. MacGinitie, collector). 



The species is common in Alaska waters, less frequent farther south, 

 and Santa Cruz Island, southern California (34°N. Lat.) is the most 

 southern record. 



Genus DIAPEROEGIA Canu, 1918 



The ovicell continues to develop after the calcification of the tubes 

 distal to it and often surrounds a considerable number of peristomes. 

 The ooeciopore is usually not terminal and is often proximal or near 



