BRYOZOA FROM ZANZIBAR. 487 



Memhran'i'pora panhopUtes Ortmann, " Die Japan. Biy.,'" Arch. 

 Naturgesch. vol. i. p. 28, pi. ii. fig. 4 (1890). 



Mem.branipo7'a armata Waters, " On Membraniporidse," Joui'n. 

 Linn. Soc, Zool. vol. xxvi. p. 687, pi. xlvii. fig. 3 (1898). 



The specimen fi^om Wasin is in parts in the hemescharan stage, 

 in others in the bilaminate, and one in my collection from Port 

 Molle is also bilaminate. This specimen from Wasin starts from 

 a unilaminate incrusting layer, but in places the zoarium is 

 tubular. 



The distal wall of the zooecium is slightly prominent, somewhat 

 reminding us of what Busk calls the penthouse projection in 

 Aspidostoma gigajiteum B. There are no ovicells in any of the 

 specimens examined, and on most of the zooecia an avicularium 

 occurs on one side only, at the distal end, dii-ected pi-oximally, 

 while on the other side, in a long chamber, thei^e is a long gland 

 with distinct seci^eting cells (figs, 8, 9), but usually without any 

 lumen. These glands are irregular in shape, sometimes lobed, 

 and there may be two elongate lobes side by side. In all the 

 specimens seen there is a distinct calcareous bar or arch to the 

 avicularium, and there ai-e two openings on the front of the avicu- 

 larium, though sometimes the lateral projections in the aviculai-ium 

 do not meet, when there is, consequently, only one opening 

 (fig. 7). In the membrane covering the avicularian chamber 

 there is, under the mandible, a ehitinous ring wheie the peculiar 

 body* ends (fig. 9, pb.), and there are other species of Cheilo- 

 stomata with a ehitinous ring or other thickening. As we have 

 seen, there is at one side an extremely long avicularian chamber, 

 at the proximal end of which there are stout muscles (fig, 9 a) 

 attached to a very long tendon by which the mandible is closed ; 

 further up there are muscles also on bath sides of the chambei-, 

 but much more delicate than the last (fig, 9 b), and attached to a 

 shorter tendon fastened to the base of the mandible with a median 

 attachment, whereas in some species of Cheilostomata this muscle 

 is attached at each side. 



The chamber containing the glands (fig. 9, gc.) is also very long, 

 and may be close to the avicularian chamber of the zocEcium next 

 above or below, but no connection with the avicularia has been 

 found after careful examination of many microtome sections. 

 On the inside there are pores like rosette-plates, and the proto- 

 plasmic threads from these are sometimes seen passing to the 

 gland, but no other internal opening has been found. Externally 

 there are three or four minute pores along the line of junction of 

 the zooecia, which, however, were onl}' noticed when carefully 

 sparching for openings. There are similar small pores over the 

 avicularian chamber. We have here another Bryozoan puzzle, 

 for the gland is not the same as the oral gland, and is contained 

 in a calcareous chamber without any openings except small pores. 



* This peculiar body is in many Cheilostomata contained in a slieath, liomologous 

 with the tentacular sheath, bnt in this species no sheath was found. 



