NO. 2 OSBURN : EASTERN PACIFIC BRYOZOA — CHEILOSTOMATA 437 



An abundant northern and arctic species, extending down the At- 

 lantic coast to Cape Cod, Massachusetts, and on the Pacific coast to 

 Oregon, O'Donoghue recorded it from a number of localities in British 

 Columbia. 



Hancock collections. Not taken in the Hancock dredgings, but there 

 are specimens from the "Albatross" Sta. D.2886, off the Oregon coast; 

 Puget Sound, Dr. J. L. Mohr, collector, and Point Barrow, Alaska, 

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



Mucronella connectens (Ridley), 1881 

 Plate 52, figs. 6-7 



Mucronella ventricosa var. connectens, Ridley, 1881:451. 

 Escharella indivisa Levinsen, 1916:450. 

 Mucronella indivisa, Osburn, 1932:14. 

 Mucronella connectens, Osburn, 1936:542. 



This species has much the appearance of M. ventricosa, with which 

 Ridley associated it. On closer study it shows a number of differences 

 which are sufficient to distinguish it clearly. The size of the zooecia 

 is larger, length 0.75 to 0.95 mm, the lyrula is a broad shelf, extending 

 nearly the full width of the proximal border of the aperture, the peri- 

 stome proximally is high and thin, extended into a low point and de- 

 scending on the sides to the base of the spines (2 to 4 in number) ; the 

 aperture is somewhat larger, 0.18 to 0.20 mm wide by 0.14 long; and 

 the ovicell has a different form, narrow proximally, widest at its middle 

 and with a distinct raised lip above the orifice. The most distinctive 

 feature is the very elongate pore chambers (dietellae) limited to usually 

 two on each side, whereas in ventricosa they are small and numerous. 



Ridley described the species from Spitsbergen and figured it care- 

 fully, showing the long dietellae. Levinsen redescribed it as indivisa 

 from Greenland, apparently overlooking Ridley's description. Osburn 

 had it (A^. indivisa) from Hudson Strait and Port Burwell, Ungava, 

 and again from Greenland (M. connectens). 



Point Barrow, Alaska, not uncommon on stones at 18 to 26 fms, 

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



Mucronella labiata (Boeck MS), Levinsen, 1886 

 Plate 52, figs. 1-2 



Lepralia labiata Boeck, MS. 



Disco pora coccinea form labiata, Smitt, 1867:27. 



Mucronella labiata, Levinsen, 1886:19. 



