852 MR, A. W. WATERS ON 
close to the other pair. There are several cases where there has 
apparently been an injury, and a new branch grows from the side 
of the broken one, and then, although the original stem has had 
the double pairs of zocecia, yet the new growth may have more 
than two internodes with only a pair of zocecia, but subsequently 
there are two pairs to each, though special causes may occasion 
irregularities. The diaphragm at the base of a zoccium has one 
pore. Near the base of the zocecium there are strong muscles for 
moving the zocecium, and similar muscles occur in Jf, gracilis H.., 
although Hincks said there were none. The new species differs 
from WM. gracilis H. in the stems not branching, and in having 
four zoeecia grouped at the distal end of the internode. 
Triticella armata Verrill has the zoarial growth very similar to 
that of Mimosella, but, according to Osburn*, it has a gizzard, 
and evidently does not belong to the present group. 
The name bigeminata was suggested by Dr Harmer, who, when 
T told him that I had found aot figured this Wimosella, thought 
that he had also found it in the ‘Siboga’ material. When he 
showed me- his specimens, which are from better material than 
mine, the identity seemed to me quite clear, and, on seeing mine, 
Dr. Harmer agreed that this was the case, so that, with his 
permission, the name originally proposed has been changed. 
Loc. Ras Osowamembe, Zanzibar Channel, 10 fath. (504), 
collected by Crossland. 
There is a small fragment of another J/imosella from Chuaka, 
which I hesitate to name as it is incomplete. Just below the 
diaphragm of the main stem there is a lateral stem on each side, 
and each of these has two or three single zoecia growing direct 
from the stem and directed distally, with this free unoceupied 
stem continuing beyond the zoccia. On the lateral stem there is 
a diaphragm before and after each zocecium. In one lateral stem 
there are two plates of attachment, as if there had been two pairs 
of zoeecia, though on all the others the zocecia are uniserial. The 
zovecia are about 0°25 mm.—0°3 mm. long. The stem is about 
0-02 mm. diam. The growth of this species somewhat reminds us 
of Farrella atlantica B., which, however, has the zocecia more or Jess 
stalked, whereas in this Wimosella the base of the zocecium is 
rounded like that of Bowerbankia. In Valkeria uva L. there is a 
diaphragm above and below the group of zocecia, whereas in 
Mimosela gracilis H., F. atlantica, and this species ‘there i is only 
the one diaphragm just beyond the branches. 
FarrELLA ATLANTICA Busk. (Pl. IV. fig. 9.) 
Farrella atlantica Busk, ‘Challenger’ Exped., Zool. vol. xvii. 
p. 37, pl. vu. fig. 3 (1886); Thornely, ‘‘ Rep. Pearl-Oyster 
Fisheries of the Gulf of Manaar,” p. 128 (1905); ‘Mar. Poly. 
Ind. Ocean,” Trans. Linn. Soc. vol. xv. p. 157 (1912). 
* Osburn calls it Hippuraria, but I have shown that the genus was founded on a 
mistake, as the “stem” was a seaweed upon which it grew: see “ Rep. Sudanese 
Bry..” Journ. Linn. Soc., Zool. vol. xxxi. p. 241, 
