324 



walls. Each rosette-plate has 1—5 pores and the largest number of rosette-plates, 

 ca. 13, are found on the long wall (see fig. 3 a), along which the avicularium is 

 situated. The pore-chambers here are also provided with the the thickest walls. 



The ooecia are very strongly arched and provided with a strongly projecting 

 central part. The numerous pores are immersed in pits, which are separated by 

 a net-work of ridges and ribs. 



The avicularia occur on most of the zooecia in the colony examined, in which 

 the primary zooecium and a number of the oldest zooecia are distinct. On some 

 of them a very small avicularium with triangular mandible is found on the one 

 side of the aperture, but however they seem to increase gradually in size in the 

 zooecia which appear later, at least to a certain extent, and they are in general 

 provided with a long, narrow, pointed mandible. The more or less strongly 

 arched chamber, which is provided with scattered pores, shows a somewhat 

 different appearance in the basal part of the colony from in the part produced 

 by superficial budding. Whilst namely the avicularia in the latter part of the 

 colony are very prominent and show the mandible pointing in all possible di- 

 rections, they are in the former part partially immersed in the zooecia and situ- 

 ated along the one lateral wall of these with the mandible pointing outwards 

 and obliquely distally. 



A single small colony of this species was found on a Mollusc shell at Syra- 

 cuse by Dr. H. J. Hansen; depth 12 — 25 fm. I have later obtained colonies of 

 this species from Oran (Algiers), which in addition to small differences in the 

 form of the aperture and operculum also show a slight difference in the structure 

 of the rosette-plates, the number of pores lying between 3 and 8. 



Schizoporella spongi,tes (Pallas) Smitt. 

 Hippothoa spongites Smitt, Kgl. Svenska Vetensk. Akad. Handl. 11 B., No. 4, 

 1873, p. 42, PI. Vm, figs. 161—163. 

 (PL XVIII, figs. 4 a-d). 

 The zooecia are rectangular, weakly arched, with numerous, scattered, fairly 

 large pores, between which there are larger or smaller tubercles. Frequently 

 there is a tubercle-shaped projection proximally to the aperture. The anter of 

 the aperture is broad, almost semicircular or semielliptical with lateral margins 

 converging somewhat proximally, and its poster is on each side provided with a 

 long, low hinge-tooth. The narrow sinus, somewhat contracted at its origin, is 

 rounded at the end, and at its beginning there is as a rule a small, conical pro- 

 jection on each side, which is directed inwards. The operculum, the accessory 

 part of which gradually becomes very narrow from the broad distal part, ends 



