444 G. M. R. Levinsen. 



or angularly bent rib found in a number of the Callopora-spec'ies, 

 but it has nothing to do with the first pair of ribs as suggested 

 by Norman. Between the two calcareous layers of the ooecium is 

 seen a reticulate net-work of wavy channels, and a similar net-work 

 is also seen f. inst. in Membr. aurita. In the meshes between the 

 channels the two calcareous layers are coalesced with each other. 



Each zooecium is provided with 5 widely separated pore-cham- 

 bers, one distal and two lateral on each side. 



In a number of zooecia I have found the aperture partially 

 filled by a calcareous plate, which is perforated in the middle by 

 an ovate opening. In this plate we may discern between an outer 

 smooth portion and an inner broad belt surrounding the opening 

 and provided with a net-work of fine undulated lines. In a number 

 of cases the boundary between this belt and the outer smooth por- 

 tion is marked by 5 — 6 pores, undoubtedly representing as many 

 spines. In one case only a proximal pore is present and in a few cases 

 there are no pores. There can be no doubt that this inner belt is 

 the cryptocyst of a regenerated zooecium, and it is evidently such a 

 case which Norman mentions when he says that the membranous 

 frontal wall "is not destroyed by liquor potassæ, and thus it would 

 appear that the strengthening material is calcareous." In one of the 

 zooecia Avhich have been regenerated a portion of the wall of the old 

 zooecium has been removed to the very basal surface and the corres- 

 ponding portion of the wall of the new zooecium is distinctly seen. 

 An inspection from the basal surface shows, further, that the basal 

 outlines of the two zooecia are a little different. 



A few colonies on stones. 



St. 15, Lat. 76°35' N. Long. 18°26' W. 150 m. 



St. 72, Danmarks Havn, 10 — 15 m. 



Membranipora (Callopora) unicornis Fleming, var. armifera 



Hincks. 

 Membranipora lineata, forma americana Smitt, op. cit. 1867, pp. 366 



and 400, PI. XX, fig. 31. 



— armifera Hincks, Annals Nat. Hist., ser. 5, Vol. VI, p. 



82, PI. XI, fig. 5. 



— — Hincks, Annals Nat. Hist., ser. 6, Vol. IX, p. 



155, PI. VIII, fig. 4. 

 Membranipora Sophiœ, var. armifera Waters, Journ. Linn. Soc. Zool., 



Vol. XXVI, p. 680, PI. XLVIII, fig. 18. 

 Callopora unicornis Fleming, uar. armifera Norman, Annals Nat. Hist., 

 ser. 7, Vol. XI, p. 591, PI. XIII, figs. 10, 11. 



Numerous colonies on algæ, tunicata, balanus and stones. 



