329 



surrounds the oa?cium in Mic. Malusi arises from a calcification ol' the marginal 

 part of the ectoooecium and in Mic. decorata the distal half of the ectoooecium 

 is calcified. The distal half of the endoooecium is provided with scattered pores 

 in Mic. decorata (PI. XV, figs. 6 a— -6 c) and sometimes also in Mic. ciliata. If the 

 lack of a covering membrane in Mic. Malusi and allied species is corroborated by 

 later examination, these species which also lack avicularia ought to be referred 

 to a special genus for which the name Fenestruliiia JuUien must be employed. 



Microporella marginata Krauss. 

 Flustramorpha marginata Busk, Challenger Zoology, Vol. X, Part I, 



1884, p. 135, PI. XX, fig. 8. 

 (PI. XV, figs. 3a-f). 



The zooecia rounded hexagonal, rather strongly arched, strongly tuberculated 

 and provided with numerous scattered pores. The aperture is broader than long, 

 and the somewhat projecting anter consists of a crenulated, arched distal margin 

 and two lateral margins, somewhat convex inwards, which converge proximally. 

 The supporting beam is well-developed, without lateral teeth. The operculum, 

 which is strongly chitinized, is provided distally with a much crenulated mar- 

 ginal part and the muscles are attached to a small depression on each side within 

 its proximal end. The ascopore which has dentated margins is half-elliptical and 

 provided with an internal, narrow, elongated projection. Each zooecium is pro- 

 vided in its distal half with 9 — 10 pore-chambers with 4—6 pores in each; 2 — 3 

 are destined for the distal connection. Further, the basal part of each zooecium 

 is provided in its distal half with a small, few-pored rosette-plate and in its 

 proximal half with an opening corresponding to an opposite rosette-plate. 



The ooecia, which seem to have no pores, are exceedingly prominent and the 

 strongly arched middle part may be so strongly marked, that it sometimes has 

 a hunched appearance. 



The heterozooecium is formed as a vibraculum and seems to be present on 

 all the zo(L'cia in the colony. The large, strongly arched, oval chamber, the longi- 

 tudinal axis of which is almost parallel with that of the zooecium, is situated on 

 one side of the zooecium and does not reach over to the basal surface of the 

 zooecium. It is connected with the latter by means of 10 — 12 uniporous rosette- 

 plates. Us frontal surface is directed distally and the sword-like flagellum, which 

 is provided with an oblitpie, triangular proximal part, points outwards (fig. 3 f). 



The colony is free, two-layered, dichotomously branched and the single 

 branches, which only slightly increase in breadth distally, have 8—16 rows of 

 zooecia. The free margins of the colony are provided with a bundle of radical 



