PORINA BOREALIS. 229 



a. Zoarium erect, ramose. 



PORINA BOREALIS, Busk. 



Plate XXXI. figs. 4-6. 



PusTULiPORA GRACILIS, Sars, Eeise i Lofot. og Fium. (1850), 26. 

 Onchopora BOREALIS, BusJc, Quart. Jouru. Micr. Sc. viii. (1860), 213, 



pi. xxviii. figs. 6, 7. 

 QuADEicELLARiA GRACILIS, SoTs, Beskr. Norske Polyz. (1863), 15 : Alder, 



Quart. Journ. Micr. Sc. (n. s.) iv. (1864), 101, pi. ii. 



figs. 9-12. 

 Anarthropora BOREALIS, Smitt, Q]]fvers. K. Vet.-Ak. Forh. 1867, Bihang, 



8 and 67, pi. xxiv. figs. 25-29. 

 Tessaradoua gracile, Norman, Shetland Polyz., Eep. B. A. 1868, 309. 

 Tessaradoma boreale, Smitt, Flor. Bryoz. pt. ii. 32, pi. vi. figs. 1, 3, 4, 5. 



Zoarium white, slender, much branched dichotomously j 

 branches cylindrical, tapering somewhat towards the 

 extremity. Zooecia disposed in four longitudinal series, 

 ovate, slightly convex, separated by indistinct lines, 

 with a row of channelled pores round the margin, and 

 traversed longitudinally by delicate undulating fur- 

 rows; orifice orbicular, sometimes bilabiate, subtubular; 

 median pore placed some way (usually about one third 

 the length of the cell) below the aperture. Avicularia 

 small, circular, somewhat raised, usually one on each 

 side, a little below the aperture, and occasionally others 

 in the line of the punctures. Ooecia terminal, slightly 

 raised, transversely elliptical, with a striated surface. 



Polypide with 18-20 tentacles. 



Height of specimens about 1 inch, occasionally nearly 

 2 inches. 



Habitat. On stems of Tubularia indivisa and Sertularm, 

 &c., from deep water. 



Locality, Shetland (Barlee) ; ibid., rather local, but 

 not rare on the Outer Haaf (A. M. N.) 



Geographical Distribution. Near Bergen, 30-40 

 fathoms, on rocky ground; Christiansund ; Bejan, mouth 

 of the Trondhjems fjord ; Lofoten ; Finmark (M. Sars) : 



