PORINA BOREALIS. 229 



a. Zoarium erect, ramose. 

 PORINA BOREALIS, Busk. 



Plate YYYT. figs. 4-6. 



PUSTPUPORA GRACILIS, Sars, Reise i Lofot. og Finm. (1850), 26. 

 O.VCHOPORA BOREALIS, Bus&, Quart. Joura. Micr. So. viii. (1860), 213, 



pi. xxviii. figs. 6, 7. 

 QCADRICELLARIA GRACiLis, Sars, Beskr. Norske Polyz. (1863), 15 : Alder, 



Quart Journ. Micr. So. (n. B.) iv. (1864), 101, pi. ii. 



figs. 9-12. 

 AXARTIIROPORA BOREALIS, Smitt, CEfVers. K. Vet.-Ak. Forh. 1867, Bihang, 



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



TESSARADOMA GRACILE, Norman, Shetland Polyz., Rep. 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 ; 

 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. Ocecia 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 Sertularue, 

 &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 ; Bejau, mouth 

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



