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THE VOYAGE OE H.M.S. CHALLENGER. 
less immersed and in the oldest parts of the zoarium their site is indicated merely by a 
small circular pit close above the oral opening ; this is owing to the circumstance that 
the central circular perforated area on their front is apparently never completely calcified. 
13. Tessaradoma, Norman. 
Pustulipora (pars), Sars. 
Quadricellaria , Sars, Alder. 
Onchopora (pars), Bk. 
Anarthropora, Smitt. 
Tessaradoma, Norman, Smitt. 
Eschar a (pars), Auctt. 
Porina (pars), Hincks, nec d’Orb. 
Character. — Zoarium continuous, erect, ramose, arising from a calcareous base, or by 
radical tubes. Stem and branches cylindrical. Zocecia tubular above from production of 
the peristome A median circular pore usually -with a raised shortly tubular border on 
the front. With or without immersed avicularia, and marginal pores. 
I have preferred to retain Dr. Norman’s appellation for this genus instead of Porina 
which has been adopted by Mr. Hincks (Brit. Mar. Polyz., p. 227), simply as it would seem 
for the reason that he considers it to be identical with the Porina of M. d’Orbigny. But as 
that author’s Family Porinidae has expressly for one of its characters “ cellules entieres, 
juxtaposees sur deux plans opposes sur un seul plan fibre ou fixe ” and gives as one of 
the characters of Porina “ rameaux comprimes,” and the cells “ adossees les unes aux 
autres lateralement ; ” and as having neither “ cellules accessoires ni vesicules ovariennes,” 
and moreover cites two living species as belonging to it — Porina africana and Porina 
( Eschara ) gracilis, Lamarck, neither of which, so far as I can perceive, has any character 
in common with Tessaradoma, I see no reason to follow him. Besides this, as the term 
Porina has been used by Prof. Smitt in another sense, it will I think obviate much 
confusion if Dr. Norman’s name be retained. 
Tessaradoma boreale, Busk (sp.) (PI. XXIV. fig. 8). 
Pustulipora gracilis, Sars, Reise i Lof. og Finnm. p. 26. 
Quadricellaria gracilis, Sars, Norske Polyzoer, p. 15 ; Alder Quart. Journ. Micr. Sci., N. S., 
vol. iv. p. 101, pi. ii. figs. 9-12. 
Onchopora borealis, Bk., Ibid., vol. viii. p. 213, pi. xxviii. figs. 6-7. 
Anarthropora borealis, Smitt, Kritisk Forteckn., pp. 8, 67, pi. xxiv. figs. 25-29. 
Tessaradoma gracile, Norman, Brit. Ass. Rep., 1868, p. 309. 
Tessaradoma boreale, Smitt, Florid. Bryoz., pt. 2, p. 32, pi. vi. figs. 143-145. 
Porina borealis, Hincks, Brit. Mar. Polyz. vol. i. p. 229, pL xxxi. figs. 4-6. 
Character. — Zoarium one to two inches high or more, irregularly dichotomous. 
Branches cylindrical, subterete. Zooecia usually quadriserial, alternate, subventricose ; 
