104 BULLETIN OF THE 



mother bud. These buds may produce new ones until the whole 

 colony has attained the size of a pea ; then young buds arise anal- 

 wards of the primary polypide, and as the margin of the colony is pro- 

 truded on each side of this point, the colony becomes heart-shaped. 

 The two upper lobes of the heart are regions of great reproductive 

 activity ; they separate from each other, and thus transform the heart- 

 shaped colony into an elongated one. Through the heaping together 

 of buds effected by this process, a misproportion between the area 

 (Flachenraum) and the circumference of the colony results, and the 

 buds, which lie in longitudinal rows, soon come to be crowded. After 

 this, they each give rise to only two daughter buds, a lateral and a 

 younger median one. 



To these observations of Braem I have little to add. I have figured 

 (Plate X. Fig. 88) a young colony of Cristatella, containing about thirty 

 polypides. This was taken in the latter part of July, and is probably 

 an egg colony. My reasons for thinking so are, that the statoblasts of 

 the preceding year form colonies in the early spring ; that statoblasts 

 of any year have never been seen, like those of Alcyonella, to hatch in 

 the fall ; and that there are, occupying the centre, two polypides of 

 very nearly equal size and development, and probably therefore of 

 nearly equal age. Surrounding these are eight younger individuals, 

 nearly equal to each other in size, and these are in turn followed by two 

 generations, of thirteen and seven individuals respectively, — the last 

 generation evidently being as yet incomplete. 



As Kraepelin ('87, pp. 38, 139, 167) clearly states, the Cristatella 

 colony is comparable with those of Pectinatella, Plumatella, etc., and may 

 be derived from them by imagining a condensation of those branching 

 colonies. The radial partitions seen in Figure 88, di sep. r. } Plate X., are 

 thus homologous with the lateral walls of the branches of a Plumatella 

 colony ; and just as in the latter, so here young individuals arise near 

 the tips of the branches, and the older individuals degenerate. As in 

 Plumatella, young individuals are produced not only distad of older, but 

 also laterad, thus founding new branches, so in Cristatella we find young 

 buds having the same positions. These facts will be better appreciated 

 by a reference to Figure 1, which shows a portion of the margin of a 

 mature colony. It is here clearly seen, (1) that, as has long been known, 

 the youngest individuals are placed nearest to the margin, and that 

 therefore, as one passes towards the centre, one encounters successively 

 older and older individuals ; and (2) that, as Kraepelin ('87, Fig. 134) has 

 already figured, the older individuals are arranged in a quincunx fashion. 



