136 MARINE BIOLOGY OF THE SUDANESE RED SEA. 
grow and ultimately surrounds the ovicell (fig. 1). The mature ovicell is 
always directed laterally. 
A similar lateral pedunculate ovicell occurs in Bicellaria ciliata (L.) ; 
B. uniserialis, Hincks ; Stirparia ciliata, Robertson ; S. occidentalis, Rob. ; 
S. californica, Rob.; S. sp. 1, MS.; S. sp. 2, MS.; S. sp. 3, MS., 
Zanzibar. 
There are two or three forms with avicularia which may have to be called 
varieties of neritina, but all have similar ovicells, among them is B. robusta, 
MacG.*. Bugula calathus, Norm., B. dentata, Lamx., B. ditrupa, Busk, 
B. avicularia, L., B. Sabatieri, Calvet, B. Murrayana, Johnst., B. cucullata, 
Verrill, all have ovicells central—that is, attached by their whole width, 
commencing in the same way by a small projection over which the calcareous 
wall ultimately grows. Now all these species are so similar to B. neritina in 
most characters and in the avicularia, that we feel satisfied they all must 
remain in the same genus, in spite of the very marked difference in the ovicell. 
We have the lateral pedunculate form of ovicell in some Bicellaria and 
apparently in all Stirparia (a genus, in my opinion, most closely allied to 
Bicellaria, though not so closely to Bugula); on the other hand, in Bicellaria 
tuba, Busk, and other species of Bicellaria the ovicell is central and attached 
the whole width. 
The ovicells must be a most important character in classification, but finding 
the same two distinct forms occurring both in Bugula and in Bicellaria is a 
warning as to the care that must be exercised in using the ovicells or indeed 
any one character too exclusively. 
Loc. Atlantic, Mediterannean, Indian Ocean, Ceylon, (?) Australia, Loyalty 
Island, Rio de Janeiro, California; Honduras (6. M/.). Suez Bay, 10 fath. 
(10) ; Canal entrance, on buoy (14) ; Floating Stage (15) ; Suez (9, 13, 16, 
20) ; Khor Shinab, 10-12 fath. (3), collected by Crossland. 
BuGULA NERITINA, var. MINIMA, nov. (Plate 11. figs. 4-7.) 
Bugula neritina, Waters, “ Australian Bry.,” Ann. Mag. Nat. Hist. ser. 5, vol. xx. p. 91, 
pl. 4. figs. 8 & 15; and probably Thornely, “ Manaar,” p. 109, Rec. Indian Mus. p. 183. 
There are forms from the Red Sea in which the colour is much lighter than 
in B. neritina typica, but there are similar light brown linear pigment cells, 
both zoaria and zocecia are more delicate; the zocecia are shorter, being about 
0°65 mm. long, while the type is usually about 1-1 mm. There are, however, 
considerable variations in size; also in B. avicularia there is material 
variation in the colonies, and even in one colony I measured zocecia 0°55 long 
and others 1:1 mm. long. There are only about 6 zoccia from one bifurea- 
tion to the next in the var. minima, whereas the branches of the type are 
longer, having about 10 zoccia. The specimen from Ball’s Head, New 
* B. robusta, MacG., occurs in 8. Africa as well as in Australia. 
