BRYOZOA FROM ZANZIBAR. 849 
me by Jullien as A. semiconvoluta; Bermuda, 30 fath. (Chall.) ; 
Great Egg Harbour, N. J.; Long Island Sound (Verrill) ; Vine- 
yard Haven, Edgartown, Woods Hole, Nantucket (Osburn). 
Wasin, Brit. E. Africa, 10 fath. (500) (501), collected by Cross- 
land. 
ZOOBOTRYON PELLUCIDUM Ehrenberg. (Pl. III. figs. 4-12; 
PAP Ve tiestl2-) 
For synonyms see Waters, ‘‘ Mar. Biol. of the Sudanese Red Sea, 
Bryozoa,” Journ. Linn. Soc., Zool. vel. xxxi. p. 243, pl. iv. figs. 12, 
15 (1910), and add 22 Oshur n, “Bry. of the Tortugas Toland! 
Florida,” Pub. 182, Carnegie Inst. of W ashington, p. 218 (1914). 
The appearance of the specimens from Chases Bay, at first 
sight, suggest specific separation from Z. pellucidum, as on the 
whole length of the long internodes there are two distinct, wide 
series of zocecia closely crowded, but with vacant longitudinal spaces 
between the series. In the Naples specimens the existence of 
series of zocecia is obscured, as the zocecia in many cases seem to be 
scattered over the stem and the whole length is not usually 
covered; but an examination of the stolon of these N aples speci- 
mens after the zoecia have been removed, shows two groups of 
about four longitudinal rows of rosette-plates, so that the differ- 
ences between the Naples and Zanzibar specimens are but slight, 
although the conditions of luxuriance are very different. Huincks’s 
name of biserialis and } MacGillivray’s bilateralis would have been 
very suitable for this form. There are frequently more than 
three branches at the end of the internode, sometimes as many 
as SIX. 
The zoecia are about 0°3 mm. long, and in the sections made 
the ova are usually single, or in some cases there are two in an 
ovarium. 
The embryo is surrounded by an ovicell sac, much the same as 
in Adeonelle * and in Diplodidymia*, the crowth of the embryo 
and of the sac going on simultaneously, and in many cases they 
are so close together that at first it is difficult to distinguish the 
sac from the embryo. In these cases the ovum must pass to the 
distal end under the operculum, from where it is developed. 
On the other hand, in most of the Cheilostomata and in the 
Cyclostomata, the ovicell is formed before the embryo is ready for 
it. In the Cyclostomata the walls may be seen starting at various 
points f to ultimately unite to form the ovicell. 
The rosette-plates were first described by Reichert? in this 
species, and it does not seem that anyone, except Smitt, had 
previously described anything of the kind, but what Smitt figured 
* Waters, “ Bry. from Zanzibar,” Proc. Zool. Soc. 1913, p. 529, pl. Ixxili. figs. 3 
& 5, and p. 490, text-fig. 79. 
+ ©On the Ovicells of some Lichenopore,”’ Journ. Linn. Soc., Zool. vol. xx. pl. xv. 
fig. 6 (1888); “ Mar. Biol. Sud. Red Sea, Bry..” Journ. Linn. Soc., Zool. vol. xxxi. 
. xxv. fig. 16 (1909). 
E: Vere. Anat. Untersuch. ti. Zoobotryon pellucidus, Ehr.,” Abhand. k. Akad. der 
Wiss. Berlin, p- 276 (1869). 
