28 MR. A. W. WATERS ON THE MARINE 



C. denticulata there are a series of short internodes before gradually becoming 

 normal — however, this may be only a character of local importance. There 

 are generally 7-9 zooecia in an internode, the branches usually commence 

 after the first or second zocecium on that side, being alternate where there is 

 no ovicell, with one branch to each internode, followed in the next internode 

 by one on the other side. In the internodes with an ovicell there is usually 

 a branch after the first zooecium or near it, and a few zooecia further up is 

 the ovicell, as well as a new branch on one or both sides near to it, corre- 

 sponding with the branching and ovicell described by Harmer in his 

 C. elongata*. The ovicell, though not as short as in Harmer'.s figured 

 specimen, is short and pomiform, but does not spread out at the distal end 

 as much. It has a slit or oval opening in the distal end of the ovicell as 

 described by Harmer for both elongata and denticulata, 



The branches are fairly straight, with sometimes a slight sigmoid curve as 

 may also be found in C. denticulata. The zooscial aperture is about O'Oli mm., 

 the distance from zooecium to zooecium is about 0"26 mm., the joints are 

 black. The denticle on the outer side of the zooecium is a most inconstant 

 character in this and other species, for some internodes may have it strongly 

 marked, while it is quite absent in others. 



It would seem that round denticulata | we have a group including probably 

 C. acropora, Busk, C. sinclairensis, Busk, C. elongata, M. Edw., C. elongata, 

 Harmer, C. serrata, Waters. Whether we consider them as species or varieties 

 I cannot think that the form I figured as C. elongata %, believing it to be the 

 form described by Milne Edwards, is less entitled to a distinct position than 

 the others. Its internodes are remarkably straight, whereas Harmer describes 

 his as usually with a sigmoid curve. I suppose that about 100 internodes of 

 the form figured were examined, all straight and long with numerous zooecia, 

 and only one branch growing near the distal end. The base of the branches, 

 both main and lateral, of the Zanzibar elongata is very broad, about 0"13 mm., 

 but as this is uot much broader than in C. denticulata much importance 

 cannot be attached to it. In my paper " On some Species of Crisia," § I 

 have referred in more detail to Harmer's C. elongata, and indicated that two 



* " Polyzoa of the 'Siboga' Expedition," Ent., Ctenost. & Cyclos. p. 96 (1915). 



t The specimen of C. denticulata in the ' Challenger ' collection from St. Paul's Rock, 

 Chall. Eep. Polyzoa, Pt. II., p. 4, pi. 2. fig. 3, has short ovicells without any tubular ooeciostome, 

 the lower joints are black, and it is somewhat like Harmer's C. elongata. The specimen from 

 Macclesfield Island, Tristan Da Cunha, has the joints light, the basis rami is not wedged in, 

 and it does not seem to be denticulata. The specimen from Cape York has fairly straight 

 internodes with the branches placed high, and is not unlike my C. elongata. 



+ " Bry. from Zanzibar," Proc. Zool. Soc. 1914, pi. 1. figs. 3, 4 (1915), and see Ann. Mag. 

 Nat. Hist. ser. 8, vol. xviii. (1916) p. 474. 



§ Ann. Mag. Nat. Hist. ser. 8, vol. xviii. (1916) p. 474. 



