468 G. M. R. Levinsen. 



Rhamphostomella coniigua Nordgaard, Hydr. and Biol, Inv. p. 172, 



PI. V, figs. 18—20. 

 Lepralia vitrea Lorenz, Bryoz. v. Jan Mayen, p. 7, Taf. VII, figs. 4 — 5. 

 — — Andersson, op. cit. p. 542, Taf. 30, fig. 2. 



(PL XXI, figs. 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14). 



The zooecia, which consist of a very hard, thick glistening cal- 

 careous substance, are hexagonally rhombical, and in the young 

 colonies divided by distinct sutures. The very convex and, towards 

 the aperture, strongly ascending, wavy-nodulous surface is provided 

 with 3 — 5 small, widely distant pores, placed some way within the 

 margin. The aperture, which is seated a little proximally to the 

 distal end of the zooecium is nearly semicircular, with an almost 

 straight or faintly concave proximal margin. It is provided with a 

 well developed, not beaded, vestibular arch, and on each side with 

 a large obtusely rounded hinge-tooth. Its distal margin presents 2 — 

 5, sometimes very long, spines, the direction of which is nearly ver- 

 tical to the surface of the colony. As a rule there is found a well- 

 developed, asymmetrical peristome surrounding that portion of the 

 aperture not taken up by the spines, and consisting in most cases of 

 a higher median outwards obliquely ascending portion and two lower 

 lateral portions, more or less sharply separated from the median 

 one. The distal wall is provided with one (or two) and the distal 

 half of each lateral wall with a single pore-chamber with 1—4 pores. 

 When there is no avicularium the peristome may be symmetrical, 

 and is often more or less mucronate, but when an avicularium is 

 present the median portion is connected with the distal end of the 

 former, and by a triangular sinus separated from the adjacent lateral 

 portion of the peristome. The operculum is well chitinized and pro- 

 vided on each side with a well-developed marginal ridge. 



In most zooecia there is found a very long, immersed sac-shaped 

 avicularium, provided with a triangular mandible. It stretches from 

 about the middle of the one lateral margin and opens at the opposite 

 corner of the aperture. It is absent in a fairly large number of the 

 zooecia surrounding the ancestrula; the latter has a large nearly 

 half-elliptical aperture without peristome, surrounded by 10 spines 

 and provided with a concave proximal margin. 



The ooecia, which are developed in niche-like hollows, are elon- 

 gate, hood-shaped, somewhat compressed, and (in dry state) provided 

 with a very large, semi-elliptical or roundedly triangular obliquely 

 outwards slanting opening. They are more or less perfectly con- 

 cealed by the deposition of calcareous layers. There is found a spine 

 on each side immediately proximal to the lateral margin of the 

 opening, while the rest of the spines are included within the ooecium. 



