93 



ot small colonies oi individuals, connccted by the basal disc tVoin which Uu- whole series of buds 

 has been developed. A characteristic yrouj) o( yomiy individuals of C gracilis is represented 

 in fig. 4, but llic mass in this case consists of the products of two budding individuals, which 

 are represented respectividy by the letters A and B. A. i — 4 are deeply pigmented bodies, 

 probably representing degenerated stalks, A. i being the main stalk. The bodies of the zooids 

 had presumably been lost before or at the commencement of the degeneration of the stalks. 

 The only healthy zooid belonging to this group is the yoiing bud .-^.5. The second group (j9) 

 consists of a budding disc prolonged into the structure B. i, which is clearly the base of an 

 old stalk whose zooid has degenerated. B.2 is a pigmented bod\-, probably a stalk whose 

 degeneration took place some considerable time before the specimen was killed. B. 3 has also 

 lost its zooid, but its degeneration has not advanced far. ^9. 4 is a healthy bud which is seen from 

 behind. The limit between its collar and its metasome is distinct, while the collar is produced 

 into five arms on the right side and three on the left. The first arms of both sides already bear 

 tentacles, and each ends in a swollen knob filled with refringent vesicles, as in C. dodccalopJms. 

 The base of the third right arm of this bud is concealed by the second and fourth arms, beneath 

 which the distal part of the arm can be detected. B. 5 is a somewhat younger bud, seen from in front. 

 B . 6 is still younger, and is seen from the side. The collar and the metasome are already clearly 

 marked oft from one another, and a single pair of arms, represented by their vesicle-bearing 

 knobs, are developed, although the}- are not well shewn in the figure. B. 7 is a very young bud, 

 in which the proboscis is already marked off from the more proximal part. All these structures, 

 B.2 — i). 7, are derivatives of the disc («'.) which constitutes the base of .5". i. 



Groups of this kind occur in considerable numbers throughout the coenoecium. In at least 

 one case evidence was obtained tending to shew that degeneration of a zooid begins by the 

 throwing off of the probo.scis and collar, leaving the metasome, with the alimentary canal, attached 

 to the .stalk. The number of structures which can be interpreted in no other way than as the 

 basal ends of degenerated stalks seems to shew (I) that degeneration of the zooids is of frequent 

 occurrence, and (II) that it is usually not succeeded by any regeneration of the lo.st parts. 



One of the youngest buds observed is shewn at the base of the stalk in PI. I, fig. 7 

 (C. gracilis) and more highh- magnified in PI. III, fig. 26. The distal end of the bud is swollen 

 into an ovoid form and is easily recognisable as the future proboscis. The anterior body-cavity, 

 lined by a distinct epithelium, can clearly be seen in optical section. The swollen region 

 which intervenes between the proboscis and the base of the old stalk probably represents the 

 collar -|- metasome. 



Pig. 27 is a rather older bud of the same species, somewhat less magnified than 

 fig. 26, and is attached to the basal disc of a zooid which has not degenerated. The proboscis 

 has assumed its adult character, being already flattened in an antero-posterior direction, and it 

 is conve.x anteriorly and concave posteriorly. The collar, which could not be distinguished from 

 the metasome in the earlier stage, is novv well marked, and is growing out dorsally into the first 

 pair of arms. Both proboscis and collar have well marked cavities, but it cannot definitely be 

 ascertained whether these cavities are continuous with one another or not. 



Fig. 8 is a pcsterior view of an older bud, considerably less magnified, and corresponcling 



