166 SIDNEY F. HAEMBR. 



possessed two more of these suppressed ovicells, two ovicells 

 showing other abnormalities, and several normal ovicells. 



In another colony a normal ovicell, with a '* suppressed " 

 ovicell on a lateral branch on each side of it, was noticed. 



In another case (fig. 13) a single internode bore no less than 

 four ovicells, and the colony to which this belonged possessed, 

 in different parts, four interuodes, in each of which two ovicells 

 had been developed. It may be noted that the occurrence of 

 two ovicells, side by side, in the same internode, is described 

 by d'Orbigny^ in C. patagonica, apparently as a normal 

 feature of the species. 



These cases, and the general remarks which have been made 

 with regard to the branching of various species of Crisia, 

 show that the growth of the colony is even more definite in its 

 character than would appear from a superficial examination, 

 and that in each particular species the tendency to vary is sub- 

 ordinated to certain principles of growth, which give rise to the 

 special symmetry which characterises the species. 



The number of zooecia which compose an internode is even 

 more variable in C. ramosa than in any of the other species. 

 Generally speaking, the number is smaller near the base of the 

 colony, and larger near its periphery, although this rule is by 

 no means absolute. The length of the internode depends 

 mainly on the number of zooecia it possesses. The longest 

 which was measured was a terminal internode in which growth 

 had ceased, and which consisted of 28 units, of which the 10th 

 was an ovicell ; its total length being slightly more than 7 

 millimetres. These long internodes usually show a well-marked 

 double curve, like a much elongated S, just as was remarked 

 in C. denticulata; and they commonly bear 3, 4, or even 5 

 branches. 



The appearance of the internodes depends greatly on the 

 condition of the zooecia. Near the ends of the branches the 

 zooecia generally have very long tubular moutlis, and, for the 

 most part, contain a functional polypide. This is especially 



' D'Orbigny, A., 'Voyage dans I'Anierique nicridioiiale,' tonic v, 4" |)artic, 

 1839 and 1846, p. 7, pi. i, fig. 1. 



